Amalgam fillings have been used for 150 years. Although there is an undeniable literature on its harms, organizations such as FDA and TDB in our country continue to recognize amalgam as a safe and harmless application (1,2). In some serious websites (3), the mentioned damages of amalgam are shown as fraudulent and it is claimed that the real “sensitivity” of dentists on this issue is to make a new profit for themselves by replacing old amalgams.
On the other hand, organizations such as IAOMT (International Academy of Oral Medicine and Toxicology) and IABDM (International Academy of Biological Dentistry and Medicine) and many functional medicine experts say that amalgam fillings should not be applied under any circumstances and that comprehensive safety measures should be taken during removal.
First, let’s look at what exactly amalgam filling is. Some physicians may also name amalgam filling as silver filling. Since both names do not express the mercury content of the filling, it is possible that patients will be incomplete. The definition given on the website of the Turkish Dental Association (TDB) is as follows: “Amalgam fillings are also defined as silver fillings. Amalgam; It is obtained by mixing silver, tin and copper alloy with mercury. Mercury, which constitutes 45-50% of the mixture, creates a durable filling material by binding the metals together ”(4). The American Food and Drug Administration (FDA) also defines amalgam similarly (1). The important part of these definitions is that mercury constitutes 50% of the amalgam. Therefore, it is beneficial for patients to be aware that when it comes to silver filling or amalgam filling, a mercury-containing filling is made almost half.
The claim we hear the most is that the mercury released from the fillings is less than the mercury we get from fish and does not exceed the threshold value considered toxic in the body. I still remember how even one of my professors, who was a professor at the university, avoided this subject by saying “You get that much mercury from fish, my dear.” However, according to the 2005 WHO report, there is no specific lower value required for the toxic effects of mercury to begin to appear, so we cannot speak of a safe threshold of “that much mercury”. According to the same report, mercury can damage the nervous system, digestive system, respiratory system and immune system, and cause kidney and lung damage (5). In addition, the form of mercury taken from fish and the mercury in amalgam fillings are different from each other, and there are numerous studies about the damages of mercury from fish. In other words, it does not matter whether it is made of fish or amalgam filling, mercury can cause harm in the body in any way.
Another misconception is that the mercury in amalgam is stable and not released into the body thanks to its connections with other metals. On the contrary, amalgam fillings especially brushing, cleaning, clenching and grinding, chewing, etc. It is known that mercury vapor is released during the laying, renewal and removal of fillings. (6)
According to IAOMT’s review of scientific studies, there is an increase in mercury concentration in the specified tissues in the following cases (6 You can find many references for each of the substances in this report):
- Chewing, brushing and / or bruxism (teeth grinding)
- In the breath of those with amalgam filling and in the air in their mouths
- In the saliva of those with amalgam filling
- In the blood of those with amalgam filling
- Various organs including kidneys, liver, pituitary gland, thyroid and brain of those with amalgam filling
- In the stools of those with amalgam filling
- Depending on the amount of amalgam in the mother, amniotic fluid, umbilical cord, placenta, various organs of the fetus such as liver, kidney and brain
- In colostrum and breast milk, depending on the amount of amalgam in the mother
As it can be understood from these, the mercury in amalgam does not stay in its place, it finds new settlements by walking around the body.
Nevertheless, some people probably have no problem by removing mercury from their body easily because they have a well-functioning detox system, while some vulnerable groups are exposed to the severe destructive effects of mercury. The fact that mercury is still considered safe by some quarters is perhaps because these vulnerable groups are getting lost in the statistics. Of course, there are many people who have no problem with amalgam filling. However, there are other groups whose health is severely impaired by mercury, and unfortunately it is often not predictable who will belong to which group. Personally, as a dentist, I don’t want to gamble on anyone!
Below I have mentioned these vulnerable groups, largely referring to IAOMT’s compilation on the subject. I quoted some of the scientific studies included in the report of IAOMT as in the report, and tried to summarize some of the more interesting ones by reading it myself. I have included some other studies not included in the report.
Some genetic variations increase the effects of mercury on the body
Gene polymorphisms, the deviations seen in genes, cause some people to be more sensitive to mercury. This is, in my opinion, the most important part of the research I have read. I conclude that these genetic variations always play a role in the links between mercury and various diseases. On the other hand, since these occur only in a fraction of the population, a direct causal relationship cannot be established between mercury and these diseases, and mercury is still considered safe.
The most common form of polymorphisms are SNPs (read as snips), that is, single nucleotide polymorphisms (single nucleotide polymorphisms). There are about 10 million SNPs in the human genome, and most of them are thought to have no health impact. However, it has been proven that some SNPs can be used to predict information such as how an individual will respond to various environmental factors, drugs, toxins, and which diseases they may be prone to (7).
The following preliminary information in the introduction of the article (8), which was made on the members of the American Dental Association in 2015 and investigated whether there is a relationship between SNPs in physicians and body mercury load, is actually a summary of the situation:
“One of the major difficulties when assessing mercury risk is that although they are exposed to similar amounts of mercury […] there is a huge difference between individuals of communities in terms of mercury levels measured in hair (Canuel et al., 2005). Differences in mercury’s absorption, distribution, and excretion processes (in other words, toxicokinetics) may also play an important role in the occurrence of this distinction, although the difference in mercury content between individuals may explain to some extent the source and dose of mercury exposed. Mercury toxicokinetics may be affected by changes in, for example, functional enzymes and proteins that transport, oxidize or reduce mercury (Gundacker et al., 2010).
The study itself is as follows:
By taking hair, urine and blood samples from 380 dentists, mercury amounts and genetic sequences are obtained. The relationship between the presence of 88 SNPs, which are thought to have a role in mercury toxicokinetics, and the amount of mercury is questioned. A link between mercury levels and 38 SNPs is detected. The genes with these SNPs are genes that play a role in the control of detox systems in the body. According to the researchers, these results are a contribution to the growing literature on genetic factors that affect the accumulation and toxicity of mercury in the body.
According to the study of dentists by Echeverria et al in 2006 (9), a polymorphism in the genes encoding BDNF (brain derived neurotrophic factor) combined with the effect of mercury causes worse results in neurobehavioral tests. This polymorphism does not cause an increasing toxic response to mercury, but it does lead to a lower level of neurobehavioral abilities, and thus an increased exposure of mercury.
A similar effect was found in those with CPOX4 (coproporphorpyrinogen oxidase) polymorphism. Although mercury does not have a direct effect, it contributes to the neurobehavioral response that worsens in those with this polymorphism. (10) (11)
There were also different interpretations of the studies on 507 students aged 8-10 at the Casa Pia School in Lisbon, known as Casa Pia children. In this study, amalgam was applied to 253 children and composite fillings were applied to 254 children (the number of filling surfaces was almost the same). The mercury rate in the urine of children treated with amalgam increased by 1-1.5 micrograms / gram compared to the baseline. However, De Rouen could not detect a difference in memory, attention, visiomotor function and nerve conduction velocity in children, and even suggested that amalgam would be a more preferred option because 50% of composite fillings require renewal (12).
On the other hand, Woods, taking the children in this experiment again, concluded that mercury leads to a decrease in the success of neurobehavioral tests in children who have some gene variations. Moreover, these gene variations are not very rare variations in the general population (13).
As you can see, when the harms of mercury are mentioned, there is a group of people not reflected in the statistics. Although statistics provide us with valuable information, the fact that regulations are based on these statistics causes individual differences to be ignored. While a dentist will not harm his 5 patients who can easily expel mercury from his body and who do not have gene variations that will cause negative consequences when encountering mercury in his genetic sequence, he will not harm his 5 patients with the amalgam fillings he has made or removed without precaution, while another patient who has difficulty in removing mercury from his body and whose genetic sequence is sensitive may inadvertently trigger negative results. .
Studies on the effects of mercury on women
The reaction to mercury can also vary by gender. It has been observed that men and women differ from each other in the rate at which mercury is expelled from the body and the distribution of mercury in the body. Men generally remove mercury from their bodies faster. Also, when mercury enters the body, it tends to pass into the kidneys and urine. In women, mercury stays in the body longer, making toxic effects more likely. More of the mercury taken goes to the brain and central nervous system than in men. Studies on the rate and distribution of mercury in men and women are as follows (14):
Hongo et al. (1994) studied the rate at which mercury was cleared from the kidneys in university staff and students. They found that gender, age, and the number of amalgam fillings correlated with mercury removal rate.
Jokstad (1990), in a study of 849 members of the Norwegian Dental Association, showed that women have a mild but statistically significant urine mercury ratio compared to men (40nmol / L for women, 44nmol / L for men). Factors such as work experience and how many years of last work did not explain this difference.
Pamphlett et al. (1997) compared the uptake of inorganic mercury by motor nerve cells in the mouse brain and concentrations in the kidneys. Female mice had more mercury granules in their motor nerves than male mice, while male mice had more mercury in their kidneys than females. They concluded that the less mercury in the kidneys of the female mice led to an increase in mercury circulating in the body and increased retention by nerve cells.
Pamphlett and Coote (1998) found that mercury was seen in the motor nerves of female mice 6 hours after exposure and 12 hours after exposure in male mice.
Thomas et al. (1986) observed that mercury penetrates the brains of female mice 2.19 times more than male mice.
According to the recommendation of the American Occupational Safety and Health Act, fertile dentistry staff women should not be exposed to air containing mercury more than 10mcg / m3, and pregnant dentistry personnel should not work in a professionally mercury-containing environment. This recommendation was repeated in Koos and Lango’s study of pregnant women, fetuses and newborns, not only for dental staff but for all women (15).
In a study by Sikorski (16), it was found that there was a relationship between the amount of mercury in the hair strands of female dentists and their assistants, reproductive problems and menstrual irregularities. In other studies conducted on women working in a mercury-rich environment, it was found that up to 45% of women suffer from hypermenorrhea and hypomenorrhea (having more or less periods than normal). It has been observed that such irregularities occur in 36-45% of women, 6 months after starting work, and this rate has increased to 67% within 3 years. Moreover, in the control group, these rates are very low, such as 1%. In line with this information, the American Environmental Protection Agency (USEPA) also reported that women who are chronically exposed to mercury vapor experience more frequent menstrual irregularities and miscarriages. He also added that the mortality rate increased in the babies of women with mercury poisoning symptoms (17).
In parallel with these studies, 418 female dentist assistants who became pregnant in the last 4 years were evaluated in terms of the time required for them to become pregnant without using birth control methods. It has been determined that those working in clinics with more than 30 amalgam applications per week and poor mercury hygiene get pregnant up to 63% more difficult than the dentist assistant control group who do not apply amalgam. (Age, smoking, history of inflammatory disease in the pelvic region, frequency of sexual intercourse, race, etc. factors were also taken into account, so that it did not affect the result.) (18)
These problems that mercury can cause in women are important, but an even more important consequence of mercury to which women are exposed is that they pass it on to their babies. There are various studies showing that the mercury in the mother is transferred to the baby through amniotic fluid and breast milk.
Mercury passes through amniotic fluid and breast milk to the baby
Vimy, in his study of sheep and monkeys (19), showed that mercury passes through amalgam fillings to the fetus. Berlin stated that the amount of mercury in the blood of the fetus increased significantly at the end of pregnancy and even exceeded the amount in the mother (20).
In a study investigating the relationship between the number of amalgam fillings in the mother and the mercury burden in the fetus, baby and child (21), mercury levels in the liver, renal cortex and cerebral cortex of 108 babies and children aged 1 day to 5 years and 36 fetuses were measured. It was observed that the mercury levels in fetuses were directly proportional to the mercury content in 11-50 weeks old children and the number of amalgam fillings in mothers.
In another study from 2008 (22), the relationship between the number of amalgam fillings in the mother and the amount of mercury the fetus was exposed to was examined. That is, it was looked at whether the baby was exposed to mercury by the amalgam fillings in the mother before she was born. It has been observed that the amount of mercury in cord blood exceeds the mercury in maternal blood, confirming other studies. It has also been found that these rates are higher in newer amalgam fillings. Another interesting point in this study is that mothers consume very little fish during their pregnancy. In other words, in this study, amalgam fillings are almost the only source of mercury in the fetus. In similar studies conducted in northern countries with more fish in their diets, the researchers noted that the total mercury load in the body was even greater.
In the study of Koos et al., Which I mentioned above, examining the effects of mercury on pregnant women and the fetus, the link between mercury and spontaneous abortion and stillbirth was also revealed (15).
In one case, it was reported that during the 35 weeks of her pregnancy, a young dentist working in an amalgam environment gave birth to a baby with severe brain damage due to mercury poisoning. Although this is only about a single woman, it is actually very important in terms of showing once again how important individual differences are. I guess none of us would have wanted that woman to have a relative.
In my next article, I will talk about the effect of mercury on Alzheimer’s, MS and other nervous system diseases and the studies done on dentists and their assistants …