- Amalgams and free radicals
- Traditional dental offices will be skeptical
- Mercury fillings increase mercury levels
- Pro-amalgam studies
- Subjective health complaints decrease after amalgam removal
- Mercury levels in blood drop by half after removal of amalgam, urine levels drop by 75%
- Mercury and genetics
- Health problems caused by mercury
- Amalgams must be removed using special equipment and precautions
- What replaces the amalgam?
- Symptoms after removal
- My take: no smoking gun as of yet, BUT…
- Closing thoughts
Should you have dental amalgams removed? Will doing so expose you to more mercury than if you were to leave the fillings in place?
Are dental amalgams “safe,” as many dentists claim?
In this post, I share my experience with getting 3 dental amalgams removed, as well as current research on the impact of dental amalgams on our health.
Later in the post, Aaron weighs in with a discussion of how genetics influence mercury metabolism.
Amalgams and free radicals
Mercury exposure isn’t good for anyone, but it can be especially harmful to certain genetic variants.
A deep dive into my genetics revealed a SOD2 A16V “mutation,” which is associated with reduced levels of superoxide dismutase (SOD2), an enzyme responsible for clearing metabolic waste from the body. Put simply, SOD2 protects our cells against damage caused by free radicals. It binds with metal ions in order to function, and in the process, neutralizes them so they can’t do damage to the body. However, mercury acts like a SOD2 predator, preferentially binding with SOD2, and other enzymes, which has the effect of lowering the body’s natural antioxidant defenses.
In addition, this study found that SOD2 may be “perturbed” in mercury intolerant patients.
Traditional dental offices will be skeptical
At a recent visit to the dentist, I was shocked to find out that I had three mercury fillings. My dentist used amalgams, approximately 7 or 8 years ago, to fill some cavities in my wisdom teeth. I chose not to have two of my wisdom removed since they’d come in with zero impaction.
At first, I requested the same dentist remove the filling, which he was willing to do as long as I didn’t “tell anyone” he was performing such a questionable (in his mind) procedure.
Many traditional, and especially older dentists, will tell you there is no reason to remove amalgam fillings.
Mercury fillings increase mercury levels
Why are so many dentists skeptical about amalgam removal?
You’d assume it results from conclusive data showing mercury from fillings does not enter our blood stream, but there are multiple published studies proving just the opposite. Mercury from amalgams raises levels of mercury in our blood, urine, and brains.1234
Even this Quack Watch article on mercury fillings, written with the intention of shaming practitioners who believe metal fillings can be harmful, concedes in its first sentences that mercury fillings increase blood levels of mercury:
Mercury is found in the earth’s crust and is ubiquitous in the environment. Thus, even without amalgam fillings, everyone has small but measurable blood and urine levels. Amalgam fillings raise these levels slightly, but this has no clinical significance.
There is ample evidence that amalgams do indeed raise mercury levels, in both blood and urine, and that they do so significantly.5
Essentially, the traditional dental community says: “don’t worry about a little bit of mercury.” They hang their hat on what the government says are “safe” levels of mercury, and their assertions are not totally without merit.
There have been a number of studies that fail to find a “smoking gun” as it relates to amalgams and disease.
For example, this study followed 20,000 service men and women in New Zealand for 20 years, finding results on amalgam and disease that were “generally reassuring, and (that) provide(d) only limited evidence of an association between amalgam and disease.”6 The study did find a small uptick in multiple sclerosis incidents. Notably, the study began with subjects all younger than 26 years of age.
A study of Swedish women actually found fewer health complaints in a high amalgam group than in a group with lower amounts of amalgam filling.7
This report, by the European Commission on Health and Human Protection, argued that mercury fillings were in essence “safe,” and that it was the removal process that was the riskiest for dentists and patients:
The main exposure to mercury in individuals with amalgam restorations occurs during placement or removal of the fillings. The removal of amalgam restorations will transiently increase the exposure of individual patients to relatively high levels of mercury and there is no clinical justification for removing clinically satisfactory amalgam restorations, except in patients suspected of having allergic reactions to amalgam constituents. The mercury release during placement and removal also results in exposure to the dental personnel. However, this may be minimized by the use of appropriate clinical techniques. No studies have shown that dental personnel suffer classical signs of mercury intoxication.
The European Commission report goes on to say that amalgams will be phased out (the paper is from 2008) because of aesthetics (mercury fillings are unsightly), and because other materials are easier to install, but not because of health concerns.
because dental amalgam is neither tooth-coloured nor adhesive to remaining tooth tissues, its use has been decreasing in recent years and the alternative tooth-coloured filling materials have become increasingly more popular.
The European Commission report concedes that mercury is dangerous and toxic, it just concludes that there are a lack of studies linking amalgams to major disease.
There have been claims of causation with respect to a variety of systemic conditions, particularly neurological and psychological/psychiatric effects, including Alzheimer’s, Parkinson’s Disease, Multiple Sclerosis and also kidney disease. However, several major epidemiological studies have failed to reveal such effects.
None of the pro-amalgam findings claim that mercury fillings do not increase our serum levels of mercury, in fact, most don’t seem to measure. The European Commission report concedes that amalgams do raise levels of mercury:
Intake of elemental mercury from dental amalgams is another source contributing to the total mercury burden in humans in the general population (WHO 1990, WHO 1991).
Subjective health complaints decrease after amalgam removal
Rather than focus on “smoking gun” ailments like diseases of the brain and heart, a family of studies have instead measured patient wellness before and after removal of amalgams. These studies also tested serum mercury levels, both before, and after, removal.
This study, published in the Journal of Oral Rehabilitation in 2011, sought to investigate long term subjective health complaints in a group that retained amalgams vs. a treatment group that had amalgams removed. The starting hypothesis was that no change would be found between the groups, however, that was not what the study ended up finding.
To quote the study:
In the treatment group, there were significant reductions in intra-oral and general health complaints from inclusion into study to the 3-year follow-up. In the reference group, changes in the same period were not significant. Comparisons between the groups showed that reductions in intra-oral and general health complaints in the treatment group were significantly different from the changes in the reference group. The mechanisms behind this remain to be identified. Reduced exposure to dental amalgam, patient-centered treatment and follow-ups, and elimination of worry are factors that may have influenced the results.
As you can see from reading the above quote, the study authors aren’t willing to go “all in” on amalgam removal as the cause of improved health for the treatment group.
Mercury levels in blood drop by half after removal of amalgam, urine levels drop by 75%
However, for our purposes, it is worth noting that the serum mercury levels for the treatment group dropped by half. Urine levels were 1/4 what they were with amalgam.
This study had similar findings, in that mercury levels dropped significantly after removing amalgams, and subjective report of disease dropped after removal of the fillings.
Similarly, this study found a decrease in health complaints and mercury levels in a group who had their mercury fillings removed.
Mercury and genetics
Passing the mic to Aaron for this portion of the post.
John started this post talking about his discovery that he carries the risk allele (G) in the SNP rs4880 in his SOD2 gene, which leads to a reduced antioxidant capacity in a variety of ways (discussed in Johns previous post); so this seems a good place to start.
As discussed above SOD2, as with many other enzymes, requires metal ions in order to function correctly, typically copper, iron, manganese or nickel.8 However, mercury can often preferentially associate with enzymes, over these other metals, and has the negative effect of inhibiting enzyme activity, or even reducing the amount of enzyme present in our cells.
Very few studies have been performed in humans looking specifically at SOD2 in relation to mercury; however, there have been several studies in animal models. This paper using rats described a reduction in levels of SOD in certain regions of the rat brain which led to an accumulation of reactive oxygen species.9 A similar effect was also observed in a zebrafish model.10
Whilst no studies have looked directly at SOD2 one group has looked at total antioxidant activity (TAA) in relation to dental amalgam mercury. They describe a significant increase in salivary levels of mercury in relation to the number of amalgams present, and in women detected a significant decrease in TAA.11 When the same group looked at blood plasma they saw a similar significant result, this time affecting both men and women.12
From this you can see that increased levels of salivary and plasma mercury can impact on antioxidant activity, potentially through SOD2. So those with impaired SOD2 activity, such as those carrying the risk allele (G) in the SNP rs4880 in the SOD2 gene, can be impacted even more by high mercury levels. However, regardlessof your SOD2 genes, mercury lowers antioxidant activity by binding to SOD2 and therefore reducing the body’s ability to neutralize free radicals.
Are there any other SNPs which are associated with elevated levels of mercury, which may be indicative of poor mercury clearance?
A major area of research has been the glutahione (GSH) pathway. GSH is key in binding mercury to allow for its excretion from the body. The effects of SNPs within several key genes was assessed in this study in relation to dietary mercury intake, which I’ve summarised in the table below.
|Gene||refSNP ID||Major allele, Minor allele (Risk)||Effect|
|GSTP1||rs1695||A/G||Those carrying the G allele had lower detected mercury levels.|
|rs1138272||C/T||Those carrying the T allele had lower detected mercury levels.|
|GCLM||rs41303970||C/T||Those carrying the T allele had increased detected mercury levels.|
|GCLC||rs17883901||C/T*||Those carrying the T allele had increased detected mercury levels.|
* Only in association with rs1695
Glutathione S-transferases (GSTs) are enzymes which facilitate the binding of GSH with mercury, allowing for its subsequent clearance. When less functional due to the above SNPs less GSH-mercury binding is impaired and less can be cleared.
Glutamyl-cysteine ligases (GCLs) are enzymes which synthesise GSH, when function is impacted with the above SNPs less GSH is produced and so less mercury can be cleared.
So those with the above SNPs (the majority of the population) should potentially try and limit their exposure to mercury, with dental amalgams being a described source.
Finally, the T allele of the SNP rs148534631 located within the non-protein coding RNA LINC00578 was strongly associated with increased levels of mercury. However, as the region doesn’t code for a protein it is difficult to see how to link this with mercury accumulation.13
Health problems caused by mercury
Ok, taking back the mic from Aaron after a solid rundown of genetic variants that make mercury exposure potentially more dangerous. While genetics play a role in the body’s ability to deal with heavy metals, it’s important to remember that mercury is bad for people of all genotypes.
To borrow scenarios we’re all familiar with from popular culture, pregnant women are instructed not to eat sushi, so as not to expose their babies to mercury, and of course, we’ve all heard of the Mad Hatter.
The World Health Organization’s “Mercury and Health” webpage lists the following health concerns related to mercury:
- Exposure to mercury – even small amounts – may cause serious health problems, and is a threat to the development of the child in utero and early in life.
- Mercury may have toxic effects on the nervous, digestive and immune systems, and on lungs, kidneys, skin and eyes.
- Mercury is considered by WHO as one of the top ten chemicals or groups of chemicals of major public health concern.
- People are mainly exposed to methylmercury, an organic compound, when they eat fish and shellfish that contain the compound.
This paper by Dr. Mark Hyman is a good resource for additional research on the negative health impact of mercury.
This article, titled “Toxic Effects of Mercury on the Cardiovascular and Central Nervous Systems,” which appeared in the Journal of Biomedicine and Biotechnology in 2012, offers another comprehensive analysis of the health damage mercury causes.
The paper concludes:
chronic low doses of mercury have an important and deleterious effect on vascular function by reducing NO bioavailability. The degree of severity of mercury exposure is comparable to traditional cardiovascular risk factors, such as hypertension diabetes or hypercholesterolemia. Therefore, mercury could be considered an important risk factor for cardiovascular disease that could play a role in the development of cardiovascular events. The association between mercury exposure and an increased risk of developing cardiovascular and neurological diseases is apparent. Thus, continuous exposure to mercury can be dangerous, and current reference values, once considered to be without risk, should be reevaluated and reduced.
Amalgams must be removed using special equipment and precautions
After reviewing the research we’ve compiled above, Perhaps you’re now considering having your dental amalgams removed? If so, you should be careful about which dentist you choose to perform the procedure.
After conducting research, I learned that metal fillings must be removed by a dentist who has the proper equipment to prevent mercury exposure through the removal process. Failure to properly remove fillings will result in dangerous mercury exposure. The dental office I went to has a special suction tool (not the scientific name for the device) they use in conjunction other precautions such as a dental dam and activated charcoal. This ensures that no mercury enters your body as the old fillings are extracted. My office also based the removal of my amalgams on the International Academy of Oral Medicine and Toxicology’s protocol for removal of dental amalgams called the Safe Mercury Amalgam Removal Technique, or “SMART” for short. SMART is a fantastic resource for guidance on the proper procedures that should be in place before amalgams can be removed safely.
What replaces the amalgam?
Ironically, many who have their amalgams removed end up with fillings made with BPA, a toxic chemical associated with plastics. However, BPA fillings are not inevitable, ask your dentist what replacement material they plan to use once the amalgam is removed. When I asked my dentist what material they used as an alternative to BPA ridden plastic, they sent this email:
The material that we used for your fillings is called ACTIVA BioACTIVE. These products are strong, durable, ionic restorative resins that have the esthetics and physical properties of composites, adn release and recharge more calcium and phosphate than traditional composite material. ACTIVA BioACTIVE materials are the first dental restoratives with a bioactive resin matrix, shock-absorbing resin component, and reactive ionomer glass fillers designed to mimic the physical and chemical properties of natural teeth. The contain NO Bisphenol A, no Bis-GMA and no BPA derivatives.
Symptoms after removal
In the Journal of Oral Rehabilitation study, seven treatment group patients complained of dizziness, gastric pain, cold hands, soar throat, and other symptoms after removal. These complaints all went away within two weeks.
My take: no smoking gun as of yet, BUT…
When you review the literature on amalgams, what you don’t find is a smoking gun directly linking mercury fillings to cardiovascular disease, Parkinson’s disease, or some other ailment. Having said that, the biggest surprise to me was the undisputed fact that dental amalgams raise levels of mercury in our bodies in a major way. In fact, amalgams are one of the primary sources of mercury humans encounter in the environment. The presence of mercury fillings adds to our toxic load, and is certainly an epigenetic burden. The evidence of people feeling better having mercury fillings removed cannot be taken lightly.
The Journal of Biomedicine article summarizes my take on mercury exposure from amalgams, which is that we know mercury is bad for us, and we know that amalgams release small amounts of mercury into our bodies everyday, so why leave this “mercury faucet” running if the amalgams can be removed safely?
For people with metal fillings, the daily release of mercury is approximately 4-5 μg/day, and the more amalgams, the more mercury.14 By contrast, mercury levels are reduced substantially when amalgams are removed.
With the state of research on amalgams unclear as to how they impact health, it seems like removal is an option that should be given more respect by the dental community writ large.
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