A silver (or amalgam) filling is a mixture of approximately 50% silver/tin alloy and 50% mercury. After tooth decay is removed and cleaned, this gray colored material is packed into the tooth and shaped.
Advantages:
Silver fillings have been used for more than 125 years. Their biggest advantage is that they are quickly placed, making them relatively inexpensive. They are also relatively durable.
Disadvantages:
Silver fillings do not bond (stick) to the tooth structure and this requires the dentist to overprepare the tooth in order to undercut and retain the filling. This requires the preparation to be wider at the base and narrower at the surface. This undercut keeps the filling from falling out of the tooth. In addition, the removal of tooth structure may weaken the tooth and result in fracture when chewing hard foods. Since filllings wear down with normal use, they will eventually need to be replaced requiring even further removal of tooth structure.
Disadvantages of amalgam include possible short-term sensitivity to hot or cold after the filling is placed. The silver-colored filling is not as natural looking as one that is tooth-colored, especially when the restoration is near the front of the mouth, and shows when the patient laughs or speaks.
Though silver fillings contain some mercury, current studies do not indicate measurable health risks to patients. However, we do know that mercury is a highly toxic material that can cause neurological and kidney disease. Adults and children have even been warned to limit the consumption of certain types of fish that carry high levels of environmental mercury. Even if there are no direct risks to patients, the extensive use of mercury in fillings may have a long term environmental impact.
Alternatives:
Composite (white) fillings are an excellent alternative, limiting the removal of healthy tissue and posing no known environmental risk. In cases of extensive decay, inlays/onlays or crowns are a much better restoration.
