The dental amalgam controversy refers to the conflicting views over the use of amalgam as a filling material mainly because it contains the element mercury. Scientists agree that dental amalgam fillings leach mercury into the mouth, but studies vary widely in the amount and whether such amount presents significant health risks. Estimations run from 1-3 micrograms (µg) per day (FDA) up to 27 µg/day (Patterson). The effects of that amount of exposure are also disputed. The use of mercury in dental fillings is approved in most countries. Norway, Denmark, and Sweden have banned the use of mercury in dental amalgams over environmental concerns, and in Sweden's case also from concerns over its effect on human health.Elsewhere in the world, unused dental amalgam after a treatment is subject to strict disposal protocols, again for possible environmental reasons rather than for fear of direct toxicity to humans.
Those who advocate the use of amalgam point out that it is durable,relatively inexpensive, and easy to use. On average, resin composites last only half as long as dental amalgam (although modern composites are improving in strength) and dental porcelain is much more expensive. However, the gap between amalgam and composites may be closing. Further, concerns have been raised about the endocrine disrupting (in particular, estrogen-mimicking) effects of plastic chemicals such as bisphenol A used in composite resins.Arguably, there is more credible evidence of a possible subclinical toxic effect of composite resins compared to dental amalgam.
In addition to health and ethics issues, opponents of dental amalgam fillings point to the negative externalities of water contamination and environmental damage of mercury. This concern is especially worrisome since its use and disposal by dentists go largely unregulated in many places, including the United States. The WHO reports that mercury from amalgam and laboratory devices accounts for 53% of total mercury emissions.Separators may dramatically decrease the release of mercury into the public sewer system, where dental amalgams contribute one-third of the mercury waste,but they are not required by some states in the United States