There are actually several different materials available, and you may want to consider which would be the best for your situation.
The most common type of filling material is silver amalgam. It has been used for many years, due to its durability and strength. These fillings may last up to 15 years, and some have reported them lasting longer. Amalgam is cheaper than other materials. They are great for the chewing surfaces of molars.
On the other hand, these fillings are not aesthetically pleasing. The dark silver material is noticeable on teeth, and they main even stain the gum around the tooth. Over time, the metal may expand and contract more than other materials, causing teeth to crack. Some people are concerned about the mercury content of this type of filling.
Growing in popularity is the tooth-colored composite filling. These fillings are almost invisible since they blend into the teeth. They are more expensive than amalgam fillings and require more accuracy from the dentist. Since composite fillings harden very quickly, the bite must be thoroughly checked before the patient leaves. These fillings last on average five to seven years. They may break or chip, so they are not recommended for deep cavities on back teeth.
Gold is the most expensive filling material. These fillings last as long as amalgam and are very strong. They are perfect for deeper fillings on molars. Some patients prefer the look of gold over silver, but they are still noticeable on the tooth. Gold fillings take longer to complete. Patients usually have to make two separate visits to complete a filling. Gold and amalgam fillings should not be used near each other because an electric shock may occur.
There is no gold in my mouth. I prefer to wear precious metal as jewelry, instead of inside my mouth. I personally have a few old amalgam fillings that are holding strong after 13 years and some new composite ones as well. I'm curious to see how long the more eye-pleasing composites will last in my mouth with good dental hygiene.