Silver fillings in my opinion are not in of itself bad. For years and years, they were the material of choice. But, they do have some negatives. First and most obvious, are the cosmetics. There is nothing natural about a smile full of silver fillings. They make your teeth look darker and your smile not as clean as it could be. If my patients want these fillings replaced for this reason, I have no problems doing so.
Secondly, they cause teeth to crack. Virtually every day at my office, someone calls up and says they lost one of their old fillings. When they come in, their filling is right where it was for the past 20 years, but the enamel holding that filling in place has been broken off. The reason for this is that metal fillings expand and contract with temperature change and enamel does not. Once the enamel is cracked, all it takes is biting down on something the wrong way, and you have a broken tooth. Sometimes the fix is easy, but sometimes the tooth can break so badly that the tooth needs to be removed (see my previous post on dental implants).
The third, and most controversial, factor is mercury. This is a hot topic and one that people feel very passionate about on both sides. Some people believe that the mercury in these silver fillings cause all types of neurological conditions like Alzheimers, chronic fatigue syndrome, dimentia, etc. I personally don't know if this is true or not, so I don't recommend my patients have their silver fillings removed strictly because of the mercury. But, if a patient of mine feels strongly about it, I will do as they wish.
So, when someone comes in to my office and I see these silver fillings I ask if they bother them cosmetically and I check for any visual signs of cracks. If both of these check out, in my opinion there is no reason to replace them. But, if one or both of these is an issue, we will talk about replacement with either a tooth colored filling (called composite fillings), porcelain onlays, or porcelain crowns. Which one we choose depends upon the size of the filling, any decay present, or cracks in the enamel.
I hope this helps answer a few questions.
