By Barry Keate
Barry Keate, has lived with tinnitus over 40 years and has published 150+ research articles on numerous aspects of tinnitus. He is an expert on the condition and a well-known advocate for those with tinnitus.
I have received numerous questions about the safety of mercury in dental fillings and whether it poses a risk to people with tinnitus or is a possible cause of tinnitus. Having many dental fillings myself, some dating from the 1960’s, I decided to research this important question.
Mercury is a known neurotoxin and leads to numerous neurological problems, including hearing loss and tinnitus. On this there is universal agreement. A dispute arises, however, about whether or not dental fillings add to mercury exposure in people. That is the subject of this article.
The Internet is full of horror stories about mercury poisoning. But just because they are found on the Internet, can they be believed? Websites promise miracle cures for tinnitus, some saying it will disappear in minutes. Miracle cure weight loss programs and other quackery abound.
So I decided I was not going to be influenced by anecdotal stories, no matter how horrifying, but would look only at the scientific evidence. I was quite surprised at what I found.
First, it is necessary to discuss the details of dental amalgam fillings and a history of their use.
Dental amalgam fillings are commonly referred to as “silver fillings” but are really approximately 50% elemental mercury. Silver comprises 25-35% of the filling and the balance is varying combinations of tin, copper and zinc. Mercury, which is liquid at room temperature, dissolves many other metals. Silver, tin, copper and zinc powders are dissolved in liquid mercury to make amalgam. It takes a while for the silver and other metals to dissolve and, as they do, the amalgam hardens and assumes a permanent shape. Amalgam is placed in a cavity during the hardening process so it is pliable at first, and then hardens in the mouth.
In 17th and 18th century America, dentistry was a subspecialty of medicine. Painful or decayed teeth were either pulled or cavities were filled with molten gold – a painful and expensive procedure.
In 1833 two French dentists immigrated to the United States and introduced the use of amalgam as a dental restoration material. The medical community was well aware of the toxicity of mercury. 19th century hat makers were known to go insane from felting hats with a mercury solution. Lewis Carroll made that knowledge part of popular fiction with the Mad Hatter in the novel, Alice in Wonderland. Nonetheless, amalgam was inexpensive and easy to work with and grew in popularity.
In 1843, the American Society of Dental Surgeons (ASDS), the only US dental association at the time, declared the use of dental amalgam to be malpractice and forced all of its members to sign a pledge to abstain from using it. The ASDS also ran the two French dentists out of the country. This was the beginning of what are known in dentistry as the Amalgam Wars.
However, the ease of use, the low cost and low pain of dental amalgams led to its continued increase. In 1844 it was reported that 50% of all dental restoration in upstate New York consisted of amalgam. As the use of amalgam grew, the ASDS fell apart and in 1859 the pro-amalgam faction formed the American Dental Association (ADA), the same organization that leads the dental profession in the US today, and remains steadfast in it’s defense of amalgam.
The second amalgam war was provoked in the 1920’s by Professor Alfred E. Stock, a leading chemist at the Kaiser Wilhelm Institute in Germany. Adverse effects on his own health from mercury in the lab led him to question the supposed safety of mercury from dental amalgam. His research, concluding there were adverse health effects, was published in leading scholarly journals of the day. It touched off a debate that raged through the 1930’ without a clear resolution, only to fade away in the storm of World War II.
We are currently in the advanced stages of the third amalgam war. The argument was opened in the late 1970’s, as modern methods of detecting the presence of trace amounts of mercury in the body were introduced, including mass spectrophotometry and the Jerome mercury vapor detector.
The ADA maintains that dental amalgam is safe and inert. On its website, it states, “Dental amalgam contains elemental mercury combined with other metals such as silver, copper, tin and zinc to form a safe, stable alloy. Dental amalgam has been used for generations to fill decayed teeth that might otherwise have been lost to decay.” 1
In 1990, the ADA adopted an ethical rule (5A), which prohibits dentists from removing amalgam “for the alleged purpose of removing toxic substances from the body when performed solely at the recommendation or suggestion of the dentist…”
Oregon law provides that a dentist can be disciplined, including loss of license, for commission of a fraud against a dental consumer. They then deemed it a fraud to recommend the removal of an amalgam for the purpose of removing a toxin. Actions by the Oregon ACLU resulted in the removal of this policy in 2003.
While it isn’t clear if the ADA coined the phrase “silver fillings,” it is clear that the term is the descriptor of choice by the ADA and most dentists. The ADA’s website and its brochures, which are given to patients, consistently refer to these fillings as “silver fillings” or as “dental amalgam” but never as “mercury fillings.”
While the ADA is providing dentists with brochures to calm patients concerns about the safety of amalgam, the amalgam manufacturers place inserts with their product that warn dentists of health risks from amalgam. In 1997, Dentsply, a leading amalgam manufacturer, disclosed that amalgam is a neurotoxin (toxic to the brain and central nervous system), a nephrotoxin (toxic to the kidneys) and a lung and skin sensitizer.
The ADA’s position on the safety of amalgam has been made even more untenable by the fact that the Environmental Protection Agency (EPA) has declared amalgam to be a hazardous material and issues specific instructions for its handling and disposal. 2
I began a search for the clinical evidence that would prove or disprove the safety of dental amalgam fillings. For certain, there are some studies that show no harm from the fillings and these are used by the ADA to make their case.
The ADA website states, “Two studies in the April 19, 2006 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.”
According to JAMA, both articles, “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.” 3
We do not know for how long the children were followed. Mercury poisoning is cumulative and not expected to show immediate symptoms.
Similarly, a study published in the “International Journal of Epidemiology”” followed 20,000 people with dental amalgam fillings and looked for evidence of multiple sclerosis and chronic fatigue syndrome. They concluded, “Results were generally reassuring, and provide only limited evidence of an association between amalgam and disease.” 4 However, all the people in the study were under 26 years of age!
Then, I found studies that were very critical of amalgam fillings and deemed them a health hazard. Researchers in New York concluded that mercury vapor continually leaches from amalgam fillings at a rate of about 10-50 times the safe limit (then at 0.28 micrograms/day). They stated that mercury has been linked to birth defects, multiple sclerosis, fatigue, Alzheimer’s disease, depression, anxiety, reduced immune function, antibiotic resistance and impaired kidney function. The found mercury to be a potent killer of white blood cells and that proper removal of amalgam fillings will restore white blood counts to healthy levels. There is also evidence that the number of T-cells (an important part of immune defenses) decreases substantially when amalgam fillings are placed in the mouth, but increases again once the fillings are removed. 5
Researchers at the Rocky Mountain Institute report that removal of amalgam fillings can markedly improve the symptoms of manic-depressive illness (bipolar disorder). The concentration of mercury vapor in the mouth was measured at the start of the study and was found to increase almost 300% after chewing gum for 10 minutes. Other research has shown that 75% or more of the mercury vapor released by chewing gum is inhaled into the lungs where it enters the blood stream and subsequently passes into the brain. Some of the patients were assigned to have all their fillings removed and were later compared to those who didn’t. All were followed for 6 to 8 months after treatment. It was very clear that the patients who had their fillings removed had significant improvements in anxiety, depression, paranoia, hostility and obsessive-compulsive behavior. Some of them were able to discontinue their lithium treatment. 6
Of particular interest to people with hearing loss and tinnitus, researchers have linked mercury to hearing loss and multiple sclerosis. We know that hearing loss has a direct impact on tinnitus. This study involved seven women who had been diagnosed with MS. They underwent a standard hearing test then all their amalgam fillings were removed. Six to eight months later they retook the hearing test. Six of the seven had significant hearing improvement in the right ear and five of the seven had improvement in the left ear. Hearing improved an average of 8 dB. The researchers concluded that amalgam fillings may be a significant factor in hearing loss experienced by MS patients and could be a factor in hearing loss for others as well. 7
So far, it is not looking like mercury amalgam fillings are as harmless as the ADA would like us to believe. However, the most shocking evidence I found is yet to come and, with it, a graphic video of exactly what happens to amalgam fillings in our mouths as they age.
In following links and different search queries, I came upon the website for the International Academy of Oral Medicine and Toxicology (IAOMT). This group was founded by a small number of dentists in 1984 that were concerned about amalgam fillings and decided to research the scientific literature. The IAOMT has since grown to 500 members in North America and affiliated chapters in 14 other countries. Its Scientific Advisory Committee includes a former Chairman of the Department of Chemistry at the University of Kentucky, a Professor of Environmental and Occupational Health Sciences at the University of Washington, a Professor of Pathology at the University of Arkansas, and so on. Their aim is to promote biocompatible approaches to dentistry, endodontics, periodontics and disease prevention.
Their main article about amalgam fillings is titled “The Scientific Case Against Amalgam” and lists fully 97 clinical studies that support their conclusions. 8 It also includes a video of an extracted tooth containing an old amalgam filling. The tooth is held in the light of a miner’s black light, a pure mercury vapor discharge lamp. The only vapor that can absorb the wavelength of a mercury emission light and cast a shadow is mercury vapor. The video clearly shows gaseous clouds of mercury vapor being released by the amalgam filling. It is shocking and convincing; everyone should see it.
Please see video “Smoking Tooth.” It lasts about 8 minutes. I encourage you watch it all the way through. It is literally jaw-dropping. Make sure the sound is on so you can hear the narrative.
To my mind, this amazing video pretty much closes the case on mercury amalgam. But let’s continue the discussion.
The current best accepted reference on absorbed mercury from amalgam fillings comes from the World Health Organization proceeding of 1991. 9 This was the report of a meeting of toxicologists and environmental health specialists with few dentists and no industry lobbyists invited. The conclusion was that the average person in the industrial world with an average number of amalgam fillings and no occupational exposure to mercury would absorb between 3 – 17 micrograms per day, with an average of 10 micrograms, from the fillings; 2.3 micrograms from all dietary sources; and 0.3 micrograms from all other environmental sources. This totals, on average, 12.6 micrograms per day. The current allowable of safe intake of mercury has recently been reduced to 0.1 micrograms/ day per kilogram of body weight, set by the US Public Health Service. For me, at 170 lbs, the maximum allowable dosage would be about 7.5 micrograms per day. Many scientists think even this reduced allowable dosage is much too high.
In the late 1980’s, researchers in Calgary, Canada, used radioactive mercury to examine the question of tissue retention of mercury from amalgam fillings. They placed twelve fillings tagged with radioactive mercury in the mouth of a sheep. After 29 days, the sheep was killed and the radioactive fillings were removed. The sheep was then placed in a full body gamma ray scanner. 10
They found a high concentration of radioactivity in the mouth and jawbone from the fillings. The highest concentration of mercury was the kidneys, 7438 nanograms per gram of tissue (ng/g). The urine concentration was only 4.7 ng/g, demonstrating the inadequacy of urine samples as an indicator of mercury storage in internal organs. The order of magnitude of mercury accumulation in liver and kidneys was confirmed by further studies using radioactive fillings in sheep.
Of particular importance to this study is there is no radioactive mercury in nature, so any of it found in the sheep’s body could only have come from the fillings.
This in-depth article covers many other aspects of the problem of mercury vapor from amalgam fillings. There is far too much material to cover in this article. The website is listed in the endnotes of this article (#8) for those who wish to read it in its entirety.
There is now a significant body of evidence establishing a chain of toxic events:
- amalgam releases significant amounts of mercury vapor;
- the mercury distributes to tissues around the body and is the biggest source of mercury body burden;
- the mercury from amalgam crosses the placenta and into breast milk, resulting in significant pre- and post-partum exposures for infants;
- adverse physiological changes occur from that exposure on the immune, renal (kidneys), reproductive and central nervous systems.
Other effects of mercury poisoning include multiple sclerosis, Alzheimer’s disease, chronic fatigue syndrome, sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination, peripheral neuropathy (itching, burning or pain), profuse sweating, tachycardia (persistently faster than normal heart beat), kidney dysfunction, neuropsychiatric symptoms (emotional instability, memory impairment, insomnia) and hypertension (increased blood pressure).
Writing this article has alerted me to the dangers of amalgam fillings. I had about half of mine removed this spring, although the reason was they were so old they were cracking and falling out. I will have the rest of them removed and replaced with composite fillings before the end of the year.
My dentist did warn me that during removal, there could be a surge of released mercury vapor. It should be handled by a practitioner who is knowledgeable on the best removal techniques. Also, it can take a year or longer for the mercury in the body to clear. Daily use of high quality multivitamins and antioxidants help to chelate the mercury and remove it faster.
- 1. http://www.ada.org/public/media/releases/6009_released01.asp
- 2. Null, G. Feldman, M. Mercury dental amalgams: the controversy continues. Journal of Orthomolecular Medicine, Vol. 17, No. 2, 2nd Quarter 2002, pp 85-110
- 3. http://www.ada.org/prof/resources/pubs/adanews
- 4. Bates, M. Fawcett, J. Garrett, N. Cutress, T. Kjellstrom, T. Health effects of dental amalgam exposure: a retrospective cohort study, International Journal of Epidemiology 2004;33(4):894-902.
- 5. Null, G. Feldman, M. Mercury dental amalgams: the controversy continues. Journal of Orthomolecular Medicine, Vol. 17, No. 2, 2nd Quarter 2002, pp 85-110.
- 6. Siblerud, R. et al. Psychometric evidence that dental amalgam mercury may be an etiological factor in manic depression. Journal of Orthomolecular Medicine, Vol. 13, No. 1, First Quarter 1998, pp. 31-40.
- 7. Siblerud, R. Kienholz, E. Evidence that mercury from dental amalgam may cause hearing loss in multiple sclerosis patients.Journal of Orthomolecular Medicine, Vol.11, No. 2, Second Quarter 1996, pp. 87-94.
- 8. http://www.iaomt.org/articles
- 9. World Health Organization: Environmental Health Criteria, Vol. 118: Inorganic Mercury. Page 61. WHO, Geneva, Switzerland, 1991.
- 10. Hahn, LJ. Kloiber, R. Leininger, RW. Vimy, MJ. Lorscheider, FL. Dental “silver” tooth fillings: a source of mercury exposure revealed by whole body scan and tissue analysis. FASEB J, 3:2641-6, 1989.