zinc phosphate, glass ionomer cement, zinc poly-carboxylate and resin. Sealing amalgam restorations A varnish can be applied to the cavity wall to provide a good marginal seal. The varnish should be insoluble in water and is usually composed of a resin in a volatile solvent. When applied to the cavity, the solvent evaporates, leaving the resin behind to seal the dentinal tubules. The amalgam can then be packed into the cavity. Dental amalgam toxicity Concerns have been raised about the potential for mercury poisoning with dental amalgam when used in a dental filling. Major health and professional organizations regard amalgam as safe but questions have been raised and acute but rare allergic reactions have been reported. Critics argue that it has toxic effects that make it unsafe, both for the patient and perhaps even more so for the dental professional manipulating it during a restoration. A study by the Life Sciences Research Office found that studies on mercury vapor and dental amalgam "provided insufficient information to enable definitive conclusions." They identified several "research gaps", including: "well-controlled studies using standardized measures that evaluate whether low level [mercury vapor exposures] produce neurotoxic and/or neuropsychological effect", studies on "co-exposure to HgO and methylmercury", studies on "in utero exposure to HgO", "occupational studies on [pregnant workers] with well-defined HgO exposure", studies on the absorption of Hg2+ by the "human neonatal gut from breast milk", studies on "whether dental professionals have increased incidences of kidney disease, emotional instability, erethrism, pulmonary dysfunction, or other characteristics of occupational HgO exposure", studies on whether there exist "potential gender differences" or "genetic basis for sensitivity to mercury exposure." The removal of amalgam fillings is not recommended for reasons other than a true hypersensitivity to mercury. Mercury levels in blood and urine have been shown to rise for a short period of time following the removal of amalgam restorations and no studies have demonstrated any health gain from restoration removal. Removal involves exposure to mercury vapor released during the removal process. Amalgams also contribute to mercury toxicity in the environment. With regard to amalgam placement and removal in pregnancy, research has not shown any adverse effects for the mother or fetus. However, research is inadequate to determine the chance of harm occurring and therefore placement and removal should be avoided during pregnancy if possible. In response to The Minamata Convention on Mercury, the European Commission has confirmed its position that