31/05/2015
The major difference between composite and silver mercury amalgam fillings is the material used. Dental amalgam is a blend of several metals which are approximately 50% mercury, 25% silver, 10% tin, 10% copper, and 5% zinc. Silver fillings have been used successfully since the Tang Dynasty in 659 and has been used reliably in Germany since the 1500’s. Since the early 1800’s silver mercury amalgam fillings have been the preferred filling of choice because it is low cost, easy to place, strong, long-lasting, and very durable. In recent years its popularity has diminished somewhat because of the concern for aesthetics, environmental pollution, and the availability of improved, reliable, tooth-colored, direct composite materials. Concerns about the toxicity of mercury have made its use increasingly controversial even though the mercury in silver fillings is formed into an insoluble salt with silver, zinc, copper and tin, and is not absorbed by humans, unlike the free ethyl and methyl mercury commonly found in seafood that is absorbed into your body and blood stream. It is always ironic to listen to anti-amalgam alarmist while they are eating shrimp, lobster, clams, oysters, tuna and sea bass, while breathing mercury in the air from burning coal. The material used for composite fillings is a mixture of polymers that can adhere to the tooth surface and are hardened with a blue light. Many people prefer this type of filling because it does not contain mercury, although they do contain many polymers and chemicals. Because composite is tooth-colored, it is not easily noticeable. Composite resins are strong enough to withstand pressures from the back teeth, and generally last ten years or more, making them a practical, comfortable, and attractive alternative to metal amalgam.