There is considerable concern among scientists and the public about the hormone-mimicking properties of many chemical components of plastics, including those found in dental composites. The commonly used Bis-GMA resin uses one of the most controversial of these, Bisphenol-A (BPA).
Responsible composite manufacturers claim that there is no unreacted BPA in dental resins, and that it takes high temperatures – several hundred degrees – to liberate free BPA. Other critics say that, in fact, the ester bonds in resins are subject to hydrolysis, and BPA can be liberated in measurable quantities. We know that dental sealants can vary in the amount of BPA they leak, but at present there is no good in vitro survey of how much BPA is liberated by the major brands of composite resins. Also, we know that the world is full of plastic chemicals, and every living thing on earth has a measurable tissue level of BPA. We don’t really know if the amount of BPA released from dental composite is enough to raise a person’s exposure above the environmental background level, or if it is truly insignificant. The accompanying articles spell out the range of issues under investigation.
Mercury Amalgam Fillings and their Danger to Human Health
Millions of dentists around the world routinely use dental amalgam as a filling material in decayed teeth. Often referred to as “silver fillings”, all dental amalgams actually consist of 45-55% metallic mercury. Mercury is a known neurotoxin that can cause harm to humans, especially children, pregnant women, and fetuses. A 2005 World Health Organization (WHO) report warned of mercury: “It may cause harmful effects to the nervous, digestive, respiratory, immune systems and to the kidneys, besides causing lung damage. Adverse health effects from mercury exposure can be: tremors, impaired vision and hearing, paralysis, insomnia, emotional instability, developmental deficits during fetal development, and attention deficit and developmental delays during childhood. Recent studies suggest that mercury may have no threshold below which some adverse effects do not occur.”
There is a global effort spearheaded by the United Nations Environment Programme to reduce mercury usage, including that of dental mercury, and some countries have already banned its use. However, amalgams are still used for about 45% of all direct dental restorations worldwide, including in the United States. In fact, it has been estimated that there are currently over 1,000 tons of mercury in the mouths of Americans, which is more than half of all the mercury being used in the U.S. today. Reports and research are consistent that these mercury-containing fillings emit mercury vapors, and while these restorations are commonly referred to as “silver fillings”, “dental amalgam”, and/or “amalgam fillings”, the public is often unaware that amalgam refers to the combination of other metals with mercury. The articles on this page address the health consequences of mercury exposure.