Dental amalgam controversy Dental amalgam controversy This discussion of the dental amalgam controversy outlines the debate over whether dental amalgam (the mercury alloy in dental fillings) should be used. Supporters claim that it is safe, effective and long-lasting while critics argue that claims have been made since the 1840s that amalgam is unsafe because it may cause mercury poisoning and other toxicity. Supporters of amalgam fillings point out that it is safe, durable, relatively inexpensive, and easy to use. On average, amalgam lasts twice as long as resin composites, takes less time to place, is tolerant of saliva or blood contamination during placement
Chemical element whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the