Dental amalgam controversy an increasing number of studies with larger sample sizes are being conducted. Those who are not opposed to amalgam claim that, aside from rare and localized tissue irritation, recent evidence-based research has continued to demonstrate no ill effects from the minute amounts of mercury exposure from amalgam fillings. A 2004 systematic review conducted by the Life Sciences Research Office, whose clients include the FDA and NIH, concluded that, "the current data are insufficient to support an association between mercury release from dental amalgam and the various complaints that have been attributed to this restoration material." A systematic review in 2009
Inorganic chemistry based on their properties. Partly the classification focuses on the position in the periodic table of the heaviest element (the element with the highest atomic weight) in the compound, partly by grouping compounds by their structural similarities. When studying inorganic compounds, one often encounters parts of the different classes of inorganic chemistry (an organometallic compound is characterized by its coordination chemistry, and may show interesting solid state properties). Different classifications are: Classical coordination compounds feature metals bound to "lone pairs" of electrons residing on the main group atoms of ligands such as HO, NH, Cl, and CN. In modern coordination