Position Statement of the American College of Prosthodontists
Dental amalgam is not mercury
It’s important to separate fear from facts. People who might be concerned about dental amalgam because it contains mercury can be reassured that credible scientific studies show no cause for alarm. Study after study shows amalgam is safe and effective for filling cavities. Mercury exists in set amalgam as inter-metallic chemical compounds, for example with silver and copper, not as elemental mercury. This is similar to the sodium in table salt; both sodium and chloride can be toxic alone but not when combined.
Measured levels of amalgam-derived mercury in organs, blood and urine are quite low, consistent with absorption of only 1 microgram/day to 3 micrograms/day.1 Our average diets (fruits, vegetables, breads) expose us to five to ten times this amount.2 Fish provide much higher amounts of dietary mercury in its most toxic and absorbable form; methyl mercury. Yet children of mothers in the Seychelles having amalgam fillings and eating fish with every meal have no mercury-related neurodevelopmental outcomes at 9 months, 30 months and 5 years.3,4 The world Health Organization estimates that to reach the most subtle, pre-clinical effects in the most sensitive individuals would require from 450 to 530 amalgam surfaces.1
Dental amalgam is safe
Authoritative medical organizations (outside of dentistry) have independently reviewed the scientific literature related to neurological, degenerative, autoimmune and psychological syndromes looking at dental amalgam as a causative agent – and found nothing:
- Alzheimer’s Association
- National Multiple Sclerosis Society
- Institute of Neurotoxicology and Neurological Disorders (Autism)
- American Academy of Pediatrics
Many organizations outside of dentistry have also reviewed the scientific literature looking for any credible link between dental amalgam fillings and general health problems – and have found none:
- U.S. Food and Drug Administration
- National Institutes of Health
- U.S. Public Health Service
- U.S.P.H.S. Centers for Disease Control and Prevention
- World Health Organization
- European Commission
Two prospective clinical trials (7 years) compared the neurobehavioral, neuropsychological and renal effects in children receiving dental amalgam versus resin-based composites. No adverse effects were found in either study, other than a higher re-treatment rate for children with resin-based composite fillings.5,6
Dental amalgam is effective – no true direct filling “substitute” yet exists
Amalgam fillings are considered less expensive to place and generally last much longer than any other material directly placed as a filling. While plastic fillings (composite) provide satisfactory service for approximately five years they are replaced at higher rates and repaired at twice the rate of amalgam.7-9 Collins et al10 reported twice the failure rate for composites as compared to amalgam by the eighth year. By 10 to 11 years, failure rates as high as 40% to 50% have been reported for composites.11, 12 More recently, multi-surface resin-based restorations were reported to be replaced and repaired at nearly twice the rate of amalgam restorations in 2,780 U.S. Navy and Marine Corps personnel during their first five years of service.13
Dental amalgam is not a major source of environmental mercury
Less than one percent of mercury released to the environment from man-made sources comes from dentistry, according to the Environmental Protection Agency. First, the vast majority of mercury in surface water is from coal-fired utility plant exhaust that travels through the air then falls back to the earth. Second, very little amalgam enters surface water, because standard dental equipment and wastewater treatment facilities capture approximately 95 percent of waste amalgam. The American Dental Association and dentists across the country are committed to recovering and recycling amalgam. To further protect the environment, the ADA encourages dentists to meet with local regulators and discuss what’s right for their community when it comes to amalgam waste disposal.
No state that has examined the issue has banned or limited dental amalgam
States where either legislative or regulatory actions were taken and terminated include:
1. Mackert JR, Berglund A: Mercury exposure from dental amalgam fillings: Absorbed dose and potential for adverse health effects. Crit Rev Oral Bio Med 1997;8:410-436.
2. LeBlanc J-C, Guérin T, Noël L, et al: Dietary exposure estimates of 18 elements from the 1st French total diet study. Food Addit Contam 2005;22:624-64
3. Watson GE, Evans K, Thurston SW: Prenatal exposure to dental amalgam in the Seychelles Child Development Nutrition Study: Associations with neurodevelopmental outcomes at 9 and 30 months. Neurotoxicology 2012;33:1511-1517
4. Watson GE, van Wijngaarden E, Love TMT, et al: Neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal dental amalgam: The Seychelles Child Development Nutrition Study. Neurotoxicol Teratol 2013;39:57-62
5. DeRouen TA, Martin MD, Leroux BG, et al. Neurobehavioral effects of dental amalgam in children: A randomized clinical trial. JAMA 2006;295:1784-1791
6. Bellinger DC, Trachtenberg F, Barregard L, et al: Neuropsychological and renal effects of dental amalgam in children. JAMA 2006;295:1775-1783.
7. Bellinger DC, Trachtenberg F, Barregard L, et al: Neuropsychological and renal effects of dental amalgam in children. JAMA 2006;295:1775-1783.
8. Soncini JA, Maserejian NN, Trachtenberg F, et al: The longevity of amalgam versus compomer/composite restorations in posterior primary and permanent teeth. Findings from the New England Children’s amalgam trial. J Am Dent Assoc 2007;138:763-771.
9. Mjör IA, Jokstad A: Five-year study of Class II restorations in permanent teeth using amalgam, glass polyalkenoate (ionomer) cement and resin-based composite material. J Dent 1993;21:338-343.
10. Collins CJ, Bryant RW, Hodge KL: A clinical evaluation of posterior composite resin restorations: 8-year findings. J Dent 1998;26:311-317.
11. Jokstad A, Mjör IA, Qvist V: The age of restorations in situ. Acta Odontol Scand 1994;52:234-242.
12. Raskin A, Michotte-Theall B, Vreven J, et al: Clinical evaluation of a posterior composite 10-year report. J Dent 1999;27:13-19.
13. Simecec JW, Diefenderfer KE, Cohen ME: An evaluation of replacement rates for posterior resin-based composite and amalgam restorations in U.S. Navy and Marine Corps recruits. J Am Dent Assoc 2009;140:200-099
J. Robert Kelly, DDS, MS, DMedSc
Approved ACP Board of Directors:
November 4, 2014
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