>From a dentist... The “silver” amalgam fillings were developed around the time of the Civil War and certainly have served their purpose in dentistry for over a hundred years, but today they are not the best way to restore teeth and unquestionably have their own share of problems. Many dentists like myself haven’t even used them in our dental practice for over fifteen years. First, you should know that “silver” is actually a misnomer. They really aren’t “silver”. When first placed in the tooth the amalgam fillings are “silver colored” because the amalgam filling’s main component is mercury, up to 50%, which is silver colored. It is the mercury that imparts that color to the amalgam. Later that silver color often corrodes and discolors and the filling becomes black. The other 50% of the amalgam ingredients are lead, tin, copper, zinc and a small amount of silver. From a health standpoint alone, many researchers and physicians would argue that having mercury and lead in the mouth is not healthy. When we remove the mercury filling material it is legally categorized as “bio-hazard” and dentists are not allowed to throw it into the trash or down the drain. By law we are required to have a bio-hazard removal service come to our office to take away our “bio-hazard”materials and dispose of them in a way that does not contaminate the environment. It is amazing that the government considers mercury amalgam filling waste bio-hazard and still have not completely outlawed the usage of the material as they have done in many other countries. When you were younger John do you remember what was in the thermometers used to take your temperature? It was mercury, right? But, it’s not longer used today, is it? There are health reasons for that. Mercury is toxic. The reason it was used in thermometers was that mercury is actually a metal that is a liquid. And the reason it worked as a thermometer is that mercury expands or contracts based on the temperature. Now imagine a filling in the middle of your tooth that expands and contracts each time you eat or drink something hot or cold. When it contracts it allows bacteria to go into the tooth in between the interface of the tooth and filling. When it expands, it places internal pressure on the remaining tooth. This is what commonly produces the cracks in the enamel of the teeth around the filling. Now, most dentists are all in agreement that when a tooth has a cavity and the decay is removed that if it was a small cavity the tooth will be 10-25% weaker, if a medium cavity 25-40% weaker, if a large cavity 40-60% or more weaker. So imagine a tooth that is weaker to begin with, and then having a filling that expands and contracts thousands upon thousands of times over a period of years. At some point something has to give, and the tooth often develops cracks, and these cracks often lead to fractured teeth. You might say, doesn’t the mercury amalgam filling strengthen the tooth? The answer is a resounding no! It just fills the void of the cavity and actually relies on the strength of the remaining tooth structure. Today when dentists see teeth with leakage, which leads to decay, or visible fractures in the tooth around the filling most dentists will recommend being proactive. This means removing the old mercury amalgam filling and replacing it with a restoration that will strengthen the tooth and help keep it from breaking. The choices the dentist will typically recommend are a bonded composite filling, an onlay (usually porcelain, but many dentists still use gold on back teeth) or a crown (again, usually porcelain but sometimes gold). Obviously the choice of which of these types of restoration will depend on the size of the original filling, the amount of decay or tooth that is cracked or fractured. Your dentist should be able to explain to you why he/she makes a particular recommendation.
