Amalgam has been utilized as a restorative material in
dentistry for more than 150 years (source: Statement by the ADA to the
Government Reform Committee, US House of Representatives on “Mercury in Dental
Amalgams: An Examination of the Science”; November 14, 2002). More recently the
safety of dental amalgam has been challenged due to the fact that dental
amalgam contains mercury. Free mercury, like other heavy metals, has been shown
to be toxic. However, the mercury in dental amalgam is not free mercury and
therefore does not share the same toxic characteristics.
Nevertheless, the slightest suggestion that dental amalgam
has the potential to be toxic and may contribute to the cause of such feared
diseases as Alzheimer’s, multiple sclerosis and autism—all of which have
unknown or little understood etiology and/or no available cures—creates a
public fear and understandable concern about the safety of dental amalgam.
Given that other materials such as gold, resin-based
composites and glass ionomers can be substituted for amalgam as restorative
materials, there has been an effort to simply ban amalgam in the United States.
Those in support of such a ban have often advanced inaccurate information
regarding the ban of amalgam in other countries.
The use of amalgam as a restorative material has declined
while the use of alternative materials, primarily resin-based composite, has
increased in recent years. While some of the shift to composite can be
attributed to an increased desire for cosmetics, clearly the fear of toxicity
has also contributed to the decline in the use of amalgam. A recent study published
in the Journal of Materials Science: Materials in Medicine discovered that an increase
in BPA (bisphenol-A) concentration was found in saliva after restoration with resin-based
composite. BPA is a compound that exhibits exogenous endocrine disrupter action.
Researchers recommended gargling after these restorations to remove the excess BPA
from saliva. While this study alone does not disqualify resin-based composite
as an acceptable restorative material, it does suggest that there may be
potential safety issues related to the chemicals used in these alternative
materials. There is little doubt that these materials have yet to receive the
same level of scrutiny as amalgam.
Another effect associated with the fear of mercury
toxicity, inappropriately attributed to dental amalgam, is the removal of
adequate and serviceable existing amalgam restorations.
Summary of Evidence
One could anoint amalgam as safe empirically from its long
history of use without any documented ill-effects except for a very small
number of allergic reactions to one or more of the components in amalgam.
Nevertheless, because mercury has been shown to be toxic and one of dental
amalgam’s major components is mercury, the concern for safety is a legitimate
issue. As such, there have been a number of significant studies to determine if
amalgam is safe and the evidence supporting the safety of dental amalgam is extensive.
Numerous international studies could be cited in support of amalgam safety. For
example, Mark Berthold reported the following in the ADA News published March 16,
A new study, conducted by leading scientists from highly
regarded research and academic institutions, finds no link between amalgam
exposure and neurological function.
The article highlights the following key outcome:
“Our findings do not support the hypothesis that exposure
to amalgam produces adverse, clinically evident neurological effects,"
concludes a research team led by Albert Kingman, Ph.D., Chief, Biostatistics Core,
at the National Institute of Dental and Craniofacial Research, part of the
federal National Institutes of Health.
"The bottom line," says co-researcher James W.
Albers, M.D., Ph.D., of the University of Michigan Medical School, "is
there was no association between abnormal neurological signs and amalgam
exposure. So these findings do not support the hypothesis that amalgam exposure
produces clinically evident neurological effects."
The article further states:
Dr. Daniel M. Meyer, associate executive director, ADA
Division of Science, notes, "Amalgam is a safe dental restorative
material. This study, like the recently published report by the independent,
nonprofit Life Science Research Office, which extensively reviewed the
literature and concluded that amalgam is safe to use in people, adds to the definitive
scientific evidence attesting to amalgam's demonstrated track record of
The effect of
amalgam restorations on children has been of particular interest. Dental amalgam
contains mercury, which may have neurotoxic effects on the nervous systems of developing
children and fetuses. When amalgam fillings are placed or removed from the teeth,
they release mercury vapor. Mercury vapor is also released during chewing. It
has been suggested that this release of mercury vapor could be significant
enough to cause neurologic effects in children and fetuses.
For the purpose of this position paper, we will cite the
ADA News article written by Jennifer Garvin and published in the April 2006
issue that discusses two important studies from the Journal of the American
Medical Association related to amalgam safety:
Two studies in the April 19 issue of the Journal of the
American Medical Association conclude that children with dental amalgam
fillings do not experience adverse effects related to neurobehavioral,
neuropsychological (IQ) and kidney function, reinforcing the ADA's longstanding
position on the safety of dental amalgam.
The ADA reports that both independent studies “reinforce
the substantial body of peer-reviewed scientific literature that supports the
safety of dental amalgam.”
“Neurobehavioral Effects of Dental Amalgam in Children” and
“Neuropsychological and Renal Effects of Dental Amalgam in Children” are the
first randomized controlled trials comparing the health effects in children
treated with amalgam fillings with those treated with composite resins. The
former was conducted in Lisbon, Portugal, and involved 508 children, ages 8 to
10, who were randomly assigned amalgam or composite fillings. The latter took
place in Boston, Massachusetts and Farmingham, Maine and comprised 534
children, ages 6 to 10, who also were randomly picked to receive amalgam or
composites. Both studies were funded by the National Institute of Dental and Craniofacial
Research and were made up of children who had no previous restorations.
The ADA News article continued:
In a press release sent to media outlets across the United
States, the ADA says, “These studies support existing scientific understanding
that the minute amount of mercury released by amalgams during eating and
drinking does not affect health adversely.” The Association goes on to
reinforce that “both studies support the continued use of dental amalgam as a
Every recognized bona fide health organization including
the Centers for Disease Control (CDC), World Health Organization (WHO), Food
and Drug Administration (FDA), US Public Health Service (USPHS), National
Institutes of Health (NIH), American Medical Association (AMA), and the
American Dental Association (ADA) have deemed amalgam to be safe:
In answer to the question: “Should pregnant women and young
children use or avoid amalgam fillings?” the FDA provides a cautionary
directive as follows:
“The recent advisory panel believed that there was not
enough information to answer this question. Some other countries follow a ‘precautionary
principle’ and avoid the use of dental amalgam in pregnant women.”
Pregnant women and persons who may have a health condition
that makes them more sensitive to mercury exposure, including individuals with
existing high levels of mercury bioburden, should not avoid seeking dental
care, but should discuss options with their health practitioner.
Anti-amalgam groups have suggested that the fact that some
countries have instituted a “ban” on dental amalgam suggests that amalgam is
not safe. The U.S. Centers for Disease Control (CDC) reported the following in
their “Fact Sheet on Dental Amalgam” in December of 2001:
Sweden, Denmark, and Germany have proposed restrictions on
dental amalgam use to diminish both human exposure to and environmental release
of mercury and not because of any documented health effects associated with
exposure to dental amalgam.
Alternatives to amalgam include gold, resin-based
composites, or glass ionomers. Resin-based composites and glass ionomers are
used more extensively than gold since gold is significantly more expensive.
There are scientific studies that demonstrate that amalgam restorations placed
on stress bearing posterior teeth have greater longevity than composite
restorations. For example, references to support this finding include those from
Allan DN, “A longitudinal study of dental restorations” published in the
British Dental Journal in 1977 and Burke FJ, Sheung SW, Major IA, Wilson NH, “Restoration
longevity and analysis of reasons for the placement and replacement of
restorations provided by vocational dental practitioners and their trainers in
the United Kingdom” published in Quintessence International in 1999. Karl F.
Leinfelder, DDS, MS also published the following in his article “Do
Restorations Made of Amalgam Outlast Those Made of Resin-Based Composite?” in
JADA in August 2000:
The dental literature reports that the longevity of amalgam
is greater than that of resin-based composites. The length of survival varies
from study to study. On average, however, most amalgam restorations can be
expected to serve clinically for 10 to 12 years. Resin-based composites, on the
other hand, perform adequately for about half that time.
It should be noted that Dr. Leinfelder also goes on to
state: “However, because of the many recent improvements in resin-based
composites and a better understanding of how to place them, their length of
survival has increased substantially.”
While it can be argued that the longevity of modern dental
resins is comparable to dental amalgam, there is no evidence to date to
demonstrate that they are superior. There is a consensus among dental
practitioners that the placement of resin-based composite restorations is more
technique sensitive often requiring a dry field. Establishing good
interproximal contacts and proper occlusion, as well as the carving of occlusal
anatomy, is more difficult with composite material. There is also a consensus that
composite restorations demand a higher fee than amalgam restorations primarily
due to the increased operative time for placement and the higher cost of
materials. However, as stated earlier, it is also important to note that the
potential safety issue related to the chemicals used in these materials,
particularly resin-based composites, has been expressed recently and is an
issue that has yet to receive the same level of scrutiny as amalgam.
According to a study published in the September-October
2007 issue of Public Health Reports, the economic impact of banning amalgam
restorations would be significant:
If amalgam restorations are banned for the entire
population, the average price of restorations before 2005 and after the ban
would increase $52 from $278 to $330, and total expenditures for restorations
would increase from $46.2 billion to $49.7 billion. As the price of
restorations increases, there would be 15,444,021 fewer restorations inserted per
year. The estimated first-year impact of banning dental amalgams in the entire population
is an increase in expenditures of $8.2 billion.
Conclusions: An amalgam ban would have a substantial short-
and long-term impact on increasing expenditures for dental care, decreasing
utilization, and increasing untreated disease. Based on the available evidence,
we believe that state legislatures should seriously consider these effects when
contemplating possible restrictions on the use of amalgam restorations.
One final important distinction between amalgam and
resin-based composite is the antibacterial properties of each material. A study
conducted by Dag Orstavik at the Scandinavian Institute of Dental Materials,
NIOM, Oslo, Norway tested nine commercial dental amalgams for antibacterial
properties in vitro. He concluded:
All amalgams displayed some antibacterial properties.
More recently, N. Beyth, A. Domb, and E. Weiss published a
study in the Journal of Dentistry in 2007 concluding the following:
The present findings demonstrate potent and lasting
antibacterial properties of amalgam, which are lacking in composite resins.
This may explain the clinical observation of biofilm accumulated more on
composites compared to amalgams. It follows that the assessment of
antibacterial properties of poorly-soluble materials has to employ more than
Another recent study confirmed the anti-bacterial
properties of amalgam alloy. This study from the University of Heidelberg was
presented in a poster session at the 2006 Interscience Conference on
Antimicrobial Agents and Chemotherapy and received online news coverage from
MedPage Today (see Phend C., ICAAC: “Amalgam Dental Fillings Fend Off Bacteria
Better than Composite”; MedPage Today, Sept. 29, 2006; available at www.medpagetoday.com/2005MeetingCoverage/2005ICAACMeeting/tb/4200).
The study concluded that titanium, gold, natural enamel and
amalgam alloy were superior to resin-based composite materials in reducing the
adherence of Streptococcus mutans to dental restorations.
Based on current best evidence, it is the recommendation of
the Committee that the AADC take the following position on the use of dental
amalgam and amalgam safety.
- There does not exist at this time evidence based
scientific research to support the assertion that the mercury contained in
dental amalgam causes disease or neurological disorders in children. To the
contrary, recent peer reviewed research has demonstrated that there is no
cause-effect relationship between dental amalgam and neurological status in
children. Further, there is no valid research to support the allegation that
significant amounts of toxic mercury is leached from dental amalgam causing
diseases such as Alzheimer’s, multiple sclerosis or autism. Therefore, the
Committee supports the conclusion that dental amalgam is safe as a restorative
- There is credible evidence to support the conclusion
that the longevity of dental amalgam restorations exceeds those of resin-based
composite. However, there is also literature to support that the newer
generations of composite are reducing the longevity difference between amalgam
and composite. As such, the Committee supports the conclusion that dental
amalgam currently is more durable and cost effective than resin-based composite
as a restorative material for stress bearing posterior teeth.
- Current literature citing the ban of dental amalgam in
other countries, primarily Sweden, Denmark, and Norway, is confusing in both
the nature and reasons for the ban. Bans in other countries per se do not
constitute evidence based scientific research that dental amalgam is not safe.
In fact, most literature and articles referencing legislative bans indicate
that any bans or restrictions are related to environmental factors associated
with mercury toxicity rather than any concern about dental amalgam safety.
There is good literature and data to support the conclusion that a ban of
dental amalgam in the United States would significantly increase the cost of
dental care and likely reduce access to care, particularly among that portion
of our population that is financially disadvantaged. It is this demographic
that is most in need of dental care. On this basis, the Committee does not
support any efforts to legislate a ban of dental amalgam in the United States.
- The “precautionary principle” has been advocated for the
placement of dental amalgam in children and pregnant women. The choice of
material for the restoration of teeth should be made by the patient in consultation
with their dentist. The Committee is not endorsing nor recommending the use of
any particular restorative material. The Committee, through this position
paper, is merely supporting the conclusion that dental amalgam is a safe,
durable, and affordable dental restorative material.
- Statement by the ADA to the Government Reform Committee, US
House of Representatives on “Mercury in Dental Amalgams: An Examination of the Science”;
November 14, 2002. Found at: www.ada/prof/resources/positions/statements/statements_amalgam.pdf.
- Garvin J, ADA News, April 2006, “JAMA studies support
safety of dental amalgam”.
- FDA Center for Devices & Radiological Health, “Questions
and Answers on Dental Amalgam”; found at FDA website www.fda.gov/cdrh/consumer/amalgams.html
- Centers for Disease Control, “Dental Amalgam Use and
Benefits—Fact Sheets and FAQ’s”; found at www.cdc.gov/OralHealth/publications/factsheets/amalgam.html
- Allan DN, “A longitudinal study of dental restorations”;
British Dental Journal, 1977, 143; 87-9.
- Burke FJ, Sheung SW, Major IA, Wilson NH, “Restoration
longevity and analysis of reasons for the placement and replacement of
restorations provided by vocational dental practitioners and their trainers in
the United Kingdom”; Quintessence International, 1999, 30:234-42.
- Leinfelder KF, DDS, MS, “Do Restorations Made of Amalgam
Outlast Those Made of Resin-Based Composite?”; JADA, Vol. 131, August 2000,
- Phend C, ICAAC: “Amalgam Dental Fillings Fend Off Bacteria
Better than Composite”; MedPage Today, Sept. 29, 2006; found at www.medpagetoday.com/2005MeetingCoverage/2005ICAACMeeting/tb/400).
- Scientific Committee on Emerging and Newly Identified
Health Risks (SCENIHR), “The safety of dental amalgam and alternative dental
restoration materials for patients and users”, European Commission, May 2008
- Lauterbach M, et al, “Neurological outcomes in children
with and without amalgam-related mercury exposure”, J Am Dent Assoc, Feb 2008,
Vol 139, No 2, 138-145.
- Belinger DC, et al, “A Dose-Effect Analysis of Children’s
Exposure to Dental Amalgam and Neuropsychological Function: The New England
Children’s Amalgam Trial” , J Am Dent Assoc, Sep 2007, Vol 138, No 9, 1210-1216
- DeRouen TA, et al, “Neurobehavioral effects of dental
amalgam in children: a randomized clinical trial”, JAMA. 2006 Apr
- Bellinger DC, et al, “Neuropsychological and renal effects
of dental amalgam in children: a randomized clinical trial”, JAMA. 2006 Apr
- Woods JS, et al, “The contribution of dental amalgam to
urinary mercury excretion in children”, Environ Health Perspect. 2007 Oct;
- Delta Dental- Letter to the Food and Drug Administration
(FDA), July 2008
- ADA Council On Scientific Affairs, “Direct and indirect
restorative materials”, J Am Dent Assoc, April 2003 Vol. 134, 463-471
- Shenker B, et al, “Immune function effects of dental
amalgam in children: a randomized clinical trial”, J Am Dent Assoc, November
2008, Vol 139: 1496-1505.
- Beazoglou T, et al, “Economic Impact of Regulating the Use
of Amalgam Restorations”, Public Health Reports, September–October 2007, Volume
- National Council Against Health Fraud, Position Paper on
Amalgam Fillings, 2002
- ADA Statement on Dental Amalgam (revised July 2008)
- Employee Benefit News, “Smile
safety: Mercury fillings' risks cited by the FDA”, September 15, 2008, ebn.benefitnews.com/asset/article/695251/smilesafety-mercury-fillings-risks-cited.html?pg=
- Alternative Dr. Mcare’s Newsletter- October 2008, Vol. 5,
November 2008, Vol 6 community.icontact.com/p/naturalhealth2/newsletters/everyone/posts/alternative-drmcare-october-2008-volume-5
- Dental Amalgam: 150 years of Safety and Effectiveness- Stuart A. Greene,
- Orstavik D, Scandinavian Institute of Dental Materials, “Antibacterial
properties of and element release from some dental amalgams”; Acta Odontologica
Scandinavia, Volume 43, Issue 4, August 1985, pgs. 231-239.
- Beyh N, Domb A, Weiss E., “An in vitro quantitative
antibacterial analysis of amalgam and composite resins”; Journal of Dentistry,
March 2007, Vol. 35, Issue 3, pgs. 201-206.
- Mark Berthold, “Study Backs Amalgam”, ADA News, March 2005.
- Daniel Meyer, Associate Executive Director, ADA Division of
Science, “Review of Dental Amalgam”, found at www.lsro.org
- Sasaki N, Okuda K, Kato T, Kakishima H, Okuma H Abe K
Tachino H, Tuchida K, Kubono K. “Salivary bisphenol-A levels detected by ELISA
after restoration with composite resin”; Journal of Materials Science:
Materials in Medicine, Volume 16, No. 4, April 2005, pgs 297-300
AADC Positions Committee
Dr. Jonathan Zucker (Chair)
Dr. Clay Pesillo (Principal Author)
Dr. Rick Celko
Dr. Darlene Chan
Dr. George Koumaras (President)
Dr. Robert Laurenzano (Founder & Immediate Past
Dr. Stephanie Lepsky
Dr. Van Nelimark
Dr. Dick Portune
Dr. Ed Schooley
Dr. Cary Sun
Dr. Fred Tye
Dr. Michael Weitzner
Dr. Dave Wesley
Dr. Marc Zweig