Dental surface restorations composed of dental amalgam, a mixture of mercury, silver, tin and other metals, significantly contribute to prolonged mercury levels in the body, according to new research from the University of Georgia's department of environmental health science in the College of Public Health
Background:
Dental amalgam has been the go-to dental filling material for more than
150 years, because it’s affordable and durable. However, about half of
the compound contains mercury, a heavy metal known to be toxic at high
levels, causing brain, heart, kidney, lung and immune system damage. New
research suggests that methyl mercury may cause damage even at low
levels.
According to its website, the U.S. Food and Drug Administration
considers dental amalgam fillings safe for adults, but says, “pregnant
women and parents with children under six who are concerned about the
absence of clinical data as to long-term health outcomes should talk to
their dentist.”
Mercury exposure from dental fillings is not a new concern, but previous
studies were inconsistent and limited, according to Xiaozhong “John”
Yu, assistant professor of environmental health science and co-author of
the study.
The new study:
This research, which analysed data from nearly 15,000 individuals, is
the first to demonstrate a relationship between dental fillings and
mercury exposure in a nationally representative population. The results
were published in the December issue of the journal Ecotoxicology and Environmental Safety.
“Tooth decay is one of the most prevalent chronic diseases,” said Lei
Yin, a scientist in the department of environmental health science and
the study’s lead author. “I think a majority of people have experienced
dental fillings, but the kind of materials the dentist uses isn’t
something that’s really discussed.”
“This study is trying to provide the most accurate levels of exposure,
which will form the scientific basis to make future risk assessment,” Yu
said, adding that the study was the first to also control for age,
education, ethnicity, race, gender, smoking and seafood consumption,
which is a known contributor to mercury levels in the body.
The researchers further analysed exposure by specific types of mercury
and found a significant increase in methyl mercury, the most toxic form
of mercury, related to dental fillings. Yu said this result suggests the
human gut microbiota, a collection of microorganisms living in the
intestines, may transform different types of mercury.
“As toxicologists, we know that mercury is poison, but it all depends
on the dose. So, if you have one dental filling, maybe it’s OK. But if
you have more than eight direct surface restorations, the potential risk for adverse
effect is higher,” Yu said. People with numerous dental fillings who are
also exposed to mercury from other sources, such as seafood or work
environments, are most at risk.
The results show that
individuals with more than eight fillings had about 150 percent more
mercury in their blood than those with none. The average American has
three dental fillings, while 25 percent of the population has 11 or more
fillings.
The study also looked at dental composite resins, a mercury-free
alternative for dental fillings that can release small amounts of
bisphenol A, or BPA, which may cause developmental or reproductive
damage. The results found no association between dental fillings and
urinary BPA, but further research is needed to understand BPA exposure
from resin-based materials.
“It’s important for doctors and
patients to be informed in their selections,” Yin said. “We now have an
excellent starting point to evaluate the potential risk of dental
material on human health.”
Xiao Song from the department of
epidemiology and biostatistics in the UGA College of Public Health, and
Simon Lin from the University of Washington’s Center for Pediatric
Dentistry also contributed to the study.
Data for the research
were provided by the National Center for Health Statistics, which
conducts the National Health and Nutrition Examination Survey. This work
was supported by CDC R21 OH 010473, ARDF and UGA Start-up Research
funding.
Story Source: Materials provided by University of Georgia. Note: Content may be edited for style and length.
The original study
Lei Yin, Kevin Yu, Simon Lin, Xiao Song, Xiaozhong Yu,
Associations of blood mercury, inorganic mercury, methyl mercury and bisphenol A with dental surface restorations in the U.S. population, NHANES 2003–2004 and 2010–2012, Ecotoxicol. Environm. Safety, 134/1 (2016) 213–225.
doi: 10.1016/j.ecoenv.2016.09.001 Related studies (newest first)
John Kall , Amanda Just , Michael Aschner,
What Is the Risk? Dental Amalgam, Mercury Exposure, and Human Health Risks Throughout the Life Span, in: D. Hollar (ed.), Epigenetics, the Environment, and Children’s Health Across Lifespans, Springer Switzerland (2016) 159-206.
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Dental amalgam exposure can elevate urinary mercury concentrations in children, Int. Dental J., 66 (2016) 136–143.
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Mercury Exposure and Risks from Dental Amalgam in Canada: The Canadian Health Measures Survey 2007–2009, Hum. Ecol. Risk Assess., 20/2 (2014) 433-447.
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Related EVISA Resources Link Database: All about dental amalgam Link Database: Toxicity of mercury Link database: Mercury exposure through the diet 
Related Information ADA American Dental Association: Statement on Dental Amalgam American Dental Association (ASA): Dental Amalgam: What Others Say British Dental Association (BDA): Dental amalgam - Fact file Consumers for Dental Choice: Mercury free dentistry DAMS, Dental Amalgam Mercury Solutions: Dental Amalgam Fillings European Commission Scientific Committees on Emerging and Newly Identified Health Risks (SCENIHR) and on Health and Environmental Risks (SCHER): Dental amalgam FDA: About Dental Amalgam Fillings GreenFacts: Tooth filling materials: Dental amalgams & alternative materials International Academy of Oral Medicine and Toxicology: The Scientific Case against Amalgam International Academy of Oral Medicine and Toxicology: Smooking Teeth International Academy of Oral Medicine and Toxicology: IAOMT Position Paper Against Dental Mercury Amalgam International Academy of Oral Medicine and Toxicology: A Comprehensive Review of the Toxic Effects of Mercury in Dental Amalgam Fillings on the Environment and Human Health. available from
biovitaal.nl Kickstarter: “You Put What In My Mouth?” National Health Federation: The Deadly Dangers of Mercury Contamination R. Lauer's Amalgamation Information Site (in German) UNEP: Minamata Convention on Mercury WHO: Future Use of Materials for Dental Restoration Wikipedia: Dental amalgam controversy
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