Amalgam fillings contain 48%-52% mercury. Temperature extremes in the mouth caused by hot or cold drinks and food make mercury fillings expand and contract inside the tooth. Most studies place amalgam-filling longevity at 5? -11? years. Over those 5-11 years, expansion and contraction of the fillings inevitably weaken remaining natural tooth structure. Weakened tooth structure can lead to seemingly sudden tooth breakage. Expansion and contraction can also pull the edges of amalgam fillings away from the natural tooth. When space opens between the mercury filling and the natural tooth, bacteria and debris seep under the filling. The metal of the old amalgam blocks x-rays. There is often little or no warning of incipient spread of decay, even if you have two regular exams and cleanings per year. By the time you feel pain, the nerve may already be involved.
Comparison of Restorative Materials