Should We Remove Our Amalgam Dental Fillings?
The position of the American Dental Association along with many dentists continues to insist that mercury-filled amalgam fillings are generally safe. Yet more recent research is questioning this assumption. And new research finds that dentists themselves are being poisoned by mercury exposure as they prepare and install amalgam fillings in their patients.
But does this mean that amalgams in our mouth pose enough of a threat to our health to have them removed?
Here is the American Dental Association’s general statement regarding mercury-filled amalgam fillings:
“Dental amalgam is considered a safe, affordable and durable material that has been used to restore the teeth of more than 100 million Americans. It contains a mixture of metals such as silver, copper and tin, in addition to mercury, which binds these components into a hard, stable and safe substance. Dental amalgam has been studied and reviewed extensively, and has established a record of safety and effectiveness.”
The statement linked above goes on to discuss studies and reviews of research through 2009. And certainly, the research seems clear from this article. Research has at least to that point indicated that amalgams have a measure of safety.
Yet research studies since 2009 have opened gaping holes in the assumption of amalgam safety. How do these fit in to the picture of whether amalgams are not safe, and to what extent?
The World Health Organization also discusses the safety of amalgams, but with some caveats:
“The current weight of evidence is that contemporary dental restorative materials, including dental amalgam, are considered to be safe and effective. However, adverse biological reactions to the materials do occasionally occur and they must be treated on an individual basis. The WHO recognises the importance of the continued monitoring of the safety and effectiveness of all dental restorative materials.”
But don’t amalgams increase our body’s load of mercury? Let’s look at this closely before reviewing the safety of amalgams.
Amalgams and urinary mercury levels
The typical amalgam will have about 50 percent mercury content. Will the mercury stay there within the tooth or will it seep out into the bloodstream?
According to a 2013 study from the University of Calgary that studied 2,137 people – the answer is the latter. This study included people with amalgams and people without amalgams. Each volunteer in the study underwent what is called a six-hour urinary challenge.
This research found that those people with amalgams had on average 0.55 micrograms per gram of creatinine.
The more amalgams a person had, the higher their urinary mercury levels. Those who had more than seven amalgam surfaces had between 30 percent and 50 percent higher urinary mercury levels compared to those without any amalgams.
For each amalgam surface the person had, there was an increase of urinary mercury by 0.04 micrograms. This means, for example, that a person with 30 surfaces might have close to 1.2 micrograms more mercury in their urine.
In another recent study, published in the International Journal of Pediatric Dentistry, researchers tested 150 children between 9 and 14 years old. They also separated the children into two groups depending upon whether their diet contained significant seafood or not (seafood contains significant mercury).
This study found, after seafood was cancelled out, that urinary mercury levels in the children with amalgams were significantly higher. The average urinary mercury level of kids with amalgams was 1.59 micrograms per liter. Average urinary mercury levels of kids without amalgams averaged only 0.0130 micrograms per liter.
Blood levels of mercury and exhaled air
Some of these studies have also measured blood levels of mercury.
A 1998 study from the National Institute of Dental Research in Bethesda, Maryland, studied 1,127 healthy military men. They found their average urinary mercury levels were 3.09 micrograms per liter and their average blood mercury levels were 2.55 micrograms per liter.
They also found the more amalgams the men had, the greater their mercury levels in both the blood and urine.
A 1992 study from the University of Oslo tested 147 people and found that urine mercury levels and blood mercury levels were both higher in people with amalgams.
After separating mercury intake from the diet, they found also found that air exhaled from those with amalgams contained significantly higher levels of mercury than the exhaled air of those without amalgams. And in all three tests, the researchers found the more amalgam surfaces there were, the higher their mercury levels were.
Their calculations also found that people with more than 36 amalgam surfaces (many cavities will require multiple surfaces restored) will absorb between 10 and 12 micrograms of mercury per day. This means absorbed within the body’s tissues.
The military study above found that some men had as many as 66 amalgam surfaces. The average male tested had 36 surfaces.
This study found that for every ten surfaces of amalgams, there is an increase of 1 microgram per liter of mercury in the urine.
Mercury vapor and elemental mercury toxicity
Much of the mercury toxicity from amalgams come from mercury vapor. This arises from elemental mercury – differentiated from organic mercury from seafood.
As elemental mercury slowly vaporizes, it gets into the blood and thus the urine and cells.
But even greater levels of mercury vapor are released when amalgams are prepared in the dentist’s office. This also goes for when amalgams are sanded or even removed.
Mercury vapor, when breathed in or absorbed sublingually, significantly increases the blood and urinary levels of mercury. This has been determined in studies that have measured the urinary levels of mercury in patients that have had their amalgams recently removed. A study from Brazil’s University of Southern Santa Catarina is one among several.
This is in addition to the extra mercury toxicity from pieces of amalgam breaking off within the mouth during finishing work at the dentist’s office. This takes place both when amalgams are put in and sanded, along with their removal.
For example, in the Brazilian study mentioned above, urinary levels of mercury after amalgam removal were about 30 percent higher compared to prior to amalgam removal.
In a 1994 study from Germany, 17 people had their amalgams removed. This resulted in an increase of between 30 and 50 percent of urinary mercury levels. This was up to six days after removal.
Within a year, however, this study showed that urinary mercury levels returned to levels of non-exposed people. And the half-life of their higher urinary mercury levels was 95 days.
Cellular mercury levels
What about the build-up of mercury in the cells? Does the body excrete all of the mercury from the blood and urine? Some have assumed this. But such a notion runs contrary to the research.
For example, one of the studies referenced by the ADA’s article related to brain levels of mercury. The study concluded that mercury build-up in the brain wasn’t any higher in people with amalgams.
Yet this is contradicted by recent research.
Elemental mercury absorbed from vaporization can cross the blood-brain barrier. This was determined in 2013. A study found that as mercury crosses, it is oxidized to Hg2. Hg2 was found to have a strong affinity to thiol-proteins within brain cells.
A 2014 study from 17 European countries and numerous public health departments among these countries – 28 institutions in total – studied hair mercury levels among children.
Just among the Belgium group of 129 children, the researchers found that children with amalgams had significantly higher levels of mercury in their hair samples. Furthermore, the more amalgams they had, the higher their hair-mercury levels were.
The study above on 150 children also found the same thing: More amalgams equated to higher levels of mercury in hair-mineral analysis.
The question of whether higher urinary mercury levels are also retained in the cells is answered by the hair analysis research. Hair mineral analysis indicates mineral or toxin levels that are more latent. This indicates that some mercury is being taken into the cells and more slowly excreted.
Do amalgam mercury levels harm our health?
Okay, so there is enough evidence supporting that urinary and hair levels of mercury are increased in those with amalgams. But are these levels high enough to be harmful?
Again, the ADA’s position is these levels do not pose a risk to health. This is where things get particularly sticky.
A 2010 study from Germany’s Department of Environmental and Integrative Medicine analyzed 40 studies that tested memory issues among those who were exposed to mercury. In 32 of those studies, researchers found evidence that mercury exposure was linked with memory deficits.
Furthermore, they found in autopsies of Alzheimer’s disease patients, higher levels of mercury in their brain tissues.
So yes, mercury exposure is unhealthy. But exposure levels is the question.
A 2000 study from the National Research Council of the National Academy of Sciences concluded that 85 micrograms per liter in cord blood or 58 micrograms per liter of urinary mercury was linked to neurodevelopmental effects.
These levels are quite high – well beyond those found in the research above. Population studies of urinary mercury haven’t found anyone more than 33 micrograms per liter. And average urinary levels among the population from other research is about 0.66 micrograms per liter.
Yet these levels are significantly higher than those considered safe by various international agencies.
The safe limit for healthy adults for urinary mercury is recommended by the World Health Organization as 0.99 micrograms per liter. Germany also adheres to this, with safe levels considered 1 microgram per liter. For blood levels, the U.S. Environmental Protection Agency lists 5.8 micrograms per liter, while Germany lists 2 micrograms per liter.
Yet neurological effects are still being found with levels lower than these.
Tremors among dentists
Dentists tend to have higher urinary mercury levels because they are exposed to it on a daily basis. For this reason, their average urinary levels have been found to average nearly three times the level of the average person, at 1.69 micrograms per liter.
As we entertain whether amalgams really pose a health threat, let’s take a look at a large new study that examined a chronic neurological condition called tremors. Tremors are an involuntary shaking of practically any part of the body. They will most commonly occur in the hands, arms, legs and feet – but also in the head, face and mid-section. The vocal cords can also shake – causing oscillations in the voice.
A 2015 study published in the Journal of the American Dental Association followed 13,906 dentists over a 24 year period. Between 1986 and 2012, dentists were evaluated when they attended each year’s ADA annual meeting.
The researchers analyzed urinary mercury levels over this period. They also estimated each dentists’ mercury exposure levels over time. Then they compared these exposures to the incidence of tremors among the dentists.
The research found that both those who had higher levels of urinary mercury and higher exposure levels had a greater incidence of tremors. They found that higher mercury levels were associated with a 10 percent increase in tremors among the entire population of dentists, and a 13 percent increased incidence of tremors among younger dentists.
The good news of this research, however, is they also found that mercury exposure has been decreasing among dentists over time. This could be the result of less amalgam use. But the greater reason is most likely the increased use of masks and other protective gear to prevent breathing in mercury vapors. This has been something that occupational safety officials have been pressing for in dentist’s offices.
The researchers concluded:
“Occupational elemental mercury exposure in US dentists decreased over time and now is approaching that of the general population. Our results suggest a positive association between elemental mercury exposure and tremor.”
Neurological effects of mercury toxicity
The point regarding “approaching that of the general population” concerns many of us who have had amalgams installed in our teeth over the years. Dentists have become more and more careful about their exposure to mercury over the years. But those of us who have received amalgams over the years have had increased exposure due to the increased number of amalgam surfaces.
But is this enough to provoke neurological problems? Possibly.
For example, a study of children from the University of Washington found that greater exposure to mercury amalgams in children is linked to behavioral problems.
However, on balance, other evidence shows neurological effects of amalgams may be minimal.
For example, a 2007 study from Harvard tested 534 children between six and 10 years old. The researchers found little difference in test and behavior scores between children with greater or less amalgam surfaces.
They also found that little difference in scores in children with urinary mercury of 0.9 micrograms per gram of creatinine compared to 0.6 micrograms. The researchers stated:
“Exposure to elemental mercury in amalgam at the levels experienced by the children who participated in the trial did not result in significant effects on neuropsychological function within the 5-year follow-up period.”
But then again, in 2008, the FDA found enough evidence to make the following two announcements regarding amalgams:
“Dental amalgams contain mercury, which may have neurotoxic effects on the nervous systems of developing children and fetus.”
“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.”
Amalgams and chronic conditions
Evidence for a link between amalgam mercury exposure and chronic conditions has been published among peer-reviewed medical journals. Complaints of chronic fatigue, anxiety and depression have been notable, though not without challenge.
A review of research from Norway and the University of Kentucky stated:
“Studies have shown that chronic mercury exposure from various sources including dental amalgams is associated with numerous health complaints, including fatigue, anxiety, and depression–and these are among the main symptoms that are associated with chronic fatigue syndrome and fibromyalgia. In addition, several studies have shown that the removal of amalgams is associated with improvement in these symptoms. Although the issue of amalgam safety is still under debate, the preponderance of evidence suggests that mercury exposure from dental amalgams may cause or contribute to many chronic conditions. Thus, consideration of mercury toxicity may be central to the effective clinical investigation of many chronic illnesses, particularly those involving fatigue and depression.”
We can thus argue that a person who is experiencing symptoms of these conditions may possibly be reacting to mercury toxicity. The question here may relate to a combination of how many amalgam surfaces they have and how strong their body’s detoxification systems are.
Electromagnetic radiation and amalgams
There is a possibility that exposure to significant electromagnetic radiation could increase the leakage of the mercury in amalgams. This was documented by medical school researchers from the Bushehr University of Medical Sciences in Iran. Here is a quote from their research, as published in the journal, Reviews on Environmental Health:
“Increased release of mercury from dental amalgam restorations after exposure to electromagnetic fields such as those generated by MRI and mobile phones has been reported by our team and other researchers. We have recently shown that some of the papers which reported no increased release of mercury after MRI, may have some methodological errors. Although it was previously believed that the amount of mercury released from dental amalgam cannot be hazardous, new findings indicate that mercury, even at low doses, may cause toxicity. Based on recent epidemiological findings, it can be claimed that the safety of mercury released from dental amalgam fillings is questionable. Therefore, as some individuals tend to be hypersensitive to the toxic effects of mercury, regulatory authorities should re-assess the safety of exposure to electromagnetic fields in individuals with amalgam restorations. On the other hand, we have reported that increased mercury release after exposure to electromagnetic fields may be risky for the pregnant women.”
I have not seen the data on the research being described above. Many might in fact question the assumptions and conclusions stated in this paper. Nevertheless, there is some documentation here. Perhaps more evidence will come in this area.
The big question: Should amalgams be removed?
In terms of putting new amalgams into our mouths, there are now good mercury-free alternatives. These include different resins, which also tend to better match our teeth color – so they also look better.
But the case for removing amalgams is not so clear.
There is a cost to removing amalgams. Both a financial cost and a cost of increased mercury exposure. When amalgams are removed, the body’s burden of mercury is significantly increased. This we discussed above. It will increase by between 30 and 50 percent and take between 100 days and a year to get urine and blood levels of mercury back down to normal.
The question comes down to whether ones ongoing exposure to mercury from current amalgams will be greater than the greater exposure brought on by removing them.
This is not only a question of numbers, although the numbers are an important part of the equation. In addition to the number of amalgam surfaces, there is a relationship between a person’s age, immune system strength and other factors. And if we agree with the assumptions of the research stated above, one might include increased exposure to radiation among the factors.
We can add to this question recent research from Italy’s University of Brescia. This multi-center study examined and tested 122 workers from throughout Italy who were exposed to mercury in their occupations. These undoubtedly included many from the dental industry. They were tested against 196 healthy control patients.
The study individually tested each person’s mercury levels, together with neurological testing for behavior, cognitive function, moods and motor function. The research also tested for tremors – as did the study on dentists discussed earlier.
Among those occupationally exposed, their urinary mercury levels averaged 10.4 micrograms per gram of creatinine. The control group’s average levels were 1.9 micrograms. Both of these levels are typically considered “low levels” of mercury by many agencies, as mentioned above.
The research found those with occupational exposures had symptoms of becoming neurologically impaired. These included deficiencies in coordination and finger tapping testing.
Prolactin levels were also significantly lower in the exposed workers.
However, the research also found no neurological or motor changes occurred as a result of mercury exposure in amalgams.
But with reference to occupational exposure – even if that exposure is considered within agency norms – there should be a definite concern. The researchers stated:
“In conclusion, this study supports the finding of early alterations of motor function and neuroendocrine secretion at very low exposure levels of inorganic Hg, below the current ACGIH BEI and below the most recent exposure levels reported in the literature.”
But again, they also stated:
“On the contrary, no effects were observed as a function of dental amalgams.”
Thus we can definitely conclude that for those who are exposed to mercury in their occupations, there is a definite need for concern, and increased safety to decrease exposure.
Before reviewing amalgam removal considerations, here is a 2014 statement made by the International Academy of Oral Medicine and Toxicology, after a review of recent research on mercury responses among people with genetic differences:
“These and other studies suggest that susceptibility to mercury toxicity differs among individuals based on multiple genes, not all of which have been identified. These studies further suggest that the levels of exposure to mercury vapor from dental amalgams may be unsafe for certain subpopulations. Moreover, a simple comparison of typical exposures versus regulatory safety standards suggests that many people receive unsafe exposures. Chronic mercury toxicity is especially insidious because symptoms are variable and nonspecific, diagnostic tests are often misunderstood, and treatments are speculative at best.”
With this in mind, for those of us who have amalgams, removing them should come with a careful analysis, which can include:
1) How many amalgam surfaces do we have? The more surfaces, the greater our exposure. Review the relationships above indicating the increased exposure for each surface. This question of how many surfaces we have can easily be answered by most dentists or dental assistants in our next routine dental exam.
2) How old are we? The older we are, the greater the toxic risk during amalgam removal. For most of us, our rate of toxin clearance slows with age.
3) What kind of immune strength do we have? The less the immune system strength, the greater the risk of toxicity during amalgam removal. This is also tied to age as well.
4) Do I have a condition that is otherwise unexplained? Such as chronic fatigue or anxiety? Lower mercury exposure might help such persons. But remember that this would come after several months of heightened mercury exposure. There might also be a significant upsurge of the condition after removal.
5) Do I have greater electromagnetic exposures? A pilot or electrician, for example, will typically have greater EMF exposure, and thus might create greater sensitivity to mercury.
6) Do I have hypersensitivities to toxins? This might make or break our decision. A person who is generally less sensitive to toxins may have an increased ability to tolerate and detoxify elemental mercury as it leaches into the body. A person who is more sensitive to toxins might also be more reactive to mercury.
7) A final consideration, specifically for women, is whether we are pregnant or might become pregnant in the near future. A dose of increased mercury during pregnancy or breastfeeding could adversely affect the child. Thus any removal should come outside of the one-year window for normalized mercury levels after removal.
All of these questions should come into play in this very personal decision on amalgam removal. These should all be discussed with one’s dentist. And getting a second opinion from a biological dentist – who specializes in removing amalgams and installing their alternatives – is also a good idea.
American Dental Association. Statement on Dental Amalgam. Accessed Jan. 18, 2016.
Dutton DJ, Fyie K, Faris P, Brunel L, Emery JH. The association between amalgam dental surfaces and urinary mercury levels in a sample of Albertans, a prevalence study. J Occup Med Toxicol. 2013 Aug 29;8(1):22. doi: 10.1186/1745-6673-8-22.
FDI POLICY STATEMENT. WHO Consensus Statement on Dental Amalgam. Also approved y the FDI General Assembly in September 1997, Seoul, Korea. Accessed Jan. 18, 2016.
Khwaja MA, Abbasi MS. Mercury poisoning dentistry: high-level indoor air mercury contamination at selected dental sites. Rev Environ Health. 2014;29(1-2):29-31. doi: 10.1515/reveh-2014-0010.
Abraham JE, Svare CW, Frank CW. The effect of dental amalgam restorations on blood mercury levels. J Dent Res. 1984;63(1):71–73. doi: 10.1177/00220345840630011801.
Begerow J, Zander D, Freier I, Dunemann L. Long-term mercury excretion in urine after removal of amalgam fillings. Int Arch Occup Environ Health. 1994;66(3):209-12.
Richardson GM. Mercury Exposure and Risks from Dental Amalgam in Canada: The Canadian Health Measures Survey 2007–2009. Hum Ecol Risk Assess. 2012. 2013/05
Suzuki T, Hongo T, Abe T, Matsuo N, Inoue N. Urinary mercury level in Japanese school children: influence of dental amalgam fillings and fish eating habits. Sci Total Environ. 1993 Aug 31;136(3):213-27.
Pirard C, Koppen G, De Cremer K, Van Overmeire I, Govarts E, Dewolf MC, Van De Mieroop E, Aerts D, Biot P, Casteleyn L, Kolossa-Gehring M, Schwedler G, Angerer J, Koch HM, Schindler BK, Castaño A, Esteban M, Schoeters G, Den Hond E, Sepai O, Exley K, Horvat M, Bloemen L, Knudsen LE, Joas R, Joas A, Van Loco J, Charlier C. Hair mercury and urinary cadmium levels in Belgian children and their mothers within the framework of the COPHES/DEMOCOPHES projects. Sci Total Environ. 2014 Feb 15;472:730-40. doi: 10.1016/j.scitotenv.2013.11.028.
Nicolae A, Ames H, Quiñonez C. Dental amalgam and urinary mercury concentrations: a descriptive study. BMC Oral Health. 2013 Sep 9;13:44. doi: 10.1186/1472-6831-13-44.
Centers for Disease Control and Prevention. National Biomonitoring Program. Factsheet: Mercury. Accessed Jan. 18, 2016.
Al-Saleh I, Abduljabbar M, Al-Rouqi R, Eltabache C, Al-Rajudi T, Elkhatib R, Nester M. The extent of mercury (Hg) exposure among Saudi mothers and their respective infants. Environ Monit Assess. 2015 Nov;187(11):678. doi: 10.1007/s10661-015-4858-y.
Anglen J, Gruninger SE, Chou HN, Weuve J, Turyk ME, Freels S, Stayner LT. Occupational mercury exposure in association with prevalence of multiple sclerosis and tremor among US dentists. J Am Dent Assoc. 2015 Sep;146(9):659-668.e1. doi: 10.1016/j.adaj.2015.05.016.
Miriam Varkey I, Shetty R, Hegde A. Mercury exposure levels in children with dental amalgam fillings. Int J Clin Pediatr Dent. 2014 Sep-Dec;7(3):180-5. doi: 10.5005/jp-journals-10005-1261.
Oliveira MT, Constantino HV, Molina GO, Milioli E, Ghizoni JS, Pereira JR. Evaluation of mercury contamination in patients and water during amalgam removal. J Contemp Dent Pract. 2014 Mar 1;15(2):165-8.
Bellinger DC, Daniel D, Trachtenberg F, Tavares M, McKinlay S. Dental amalgam restorations and children’s neuropsychological function: the New England Children’s Amalgam Trial. Environ Health Perspect. 2007 Mar;115(3):440-6.
Woods JS, Heyer NJ, Russo JE, Martin MD, Farin FM. Genetic polymorphisms affecting susceptibility to mercury neurotoxicity in children: summary findings from the Casa Pia Children’s Amalgam clinical trial. Neurotoxicology. 2014 Sep;44:288-302. doi: 10.1016/j.neuro.2014.07.010.
Mutter J, Curth A, Naumann J, Deth R, Walach H. Does inorganic mercury play a role in Alzheimer’s disease? A systematic review and an integrated molecular mechanism. J Alzheimers Dis. 2010;22(2):357-74. doi: 10.3233/JAD-2010-100705.
Kern JK, Geier DA, Bjørklund G, King PG, Homme KG, Haley BE, Sykes LK, Geier MR. Evidence supporting a link between dental amalgams and chronic illness, fatigue, depression, anxiety, and suicide. Neuro Endocrinol Lett. 2014;35(7):537-52.
Mortazavi G, Mortazavi SM. Increased mercury release from dental amalgam restorations after exposure to electromagnetic fields as a potential hazard for hypersensitive people and pregnant women. Rev Environ Health. 2015 Dec 1;30(4):287-92. doi: 10.1515/reveh-2015-0017.
Edlich RF, Cross CL, Wack CA, Long WB 3rd, Newkirk AT. The food and drug administration agrees to classify mercury fillings. J Environ Pathol Toxicol Oncol. 2008;27(4):303-5.
Lucchini R, Cortesi I, Facco P, Benedetti L, Camerino D, Carta P, Urbano ML, Zaccheo A, Alessio L. Neurotoxic effect of exposure to low doses of mercury. Med Lav. 2002 May-Jun;93(3):202-14.
Homme KG, Kern JK, Haley BE, Geier DA, King PG, Sykes LK, Geier MR. New science challenges old notion that mercury dental amalgam is safe. Biometals. 2014 Feb;27(1):19-24. doi: 10.1007/s10534-013-9700-9.