As appeared in the journal Vital Link Spring 2010, the Journal of the Canadian Association of Naturopathic Doctors
One of the most controversial areas within dentistry is the concern surrounding mercury-amalgam fillings.11 Amalgam was first introduced in 1830, to wide acclaim, as it was inexpensive and easily placed in the mouth. The previous choices had been gold or extractions and eventually dentures. In 1845, The American Society of Dental Surgeons asked its members to sign a document stating that they would no longer use amalgam because of concerns regarding its possible toxicity. However, the public demand for amalgam caused most dentists to abandon their pledge, and the American Dental Society eventually disbanded. In 1859 the American Dental Association (ADA) was founded by a group of pro-amalgamists.1, 2, 3
The basic components of amalgams are mercury 50%, silver 35%, copper 6% and tin 9%–along with traces of zinc. The toxicity of mercury was well known by the time amalgam was developed, and initially the dental profession stated that, once set, the mercury did not leach out of the amalgam. However, evidence has proved that amalgam vapourizes mercury 24 hours a day from the moment it is placed in the mouth.4, 5
The ADA web site states: “Silver, copper and tin, in addition to mercury, bind these components into a hard, stable and safe substance.”6 The ADA still does not acknowledge the constant release of mercury vapour. In fact, the amount of mercury released increases after drinking hot liquids, chewing, or brushing the teeth, and takes approximately 90 minutes to settle back to the pre-stimulated rate.7 “The Smoking Tooth” video clearly illustrates this phenomenon.8
The amount of mercury an individual with amalgams absorbs is widely debated.9, 10 Upon release, mercury is inhaled; 80% of it is absorbed through the lungs into the bloodstream.7 The mercury vapour that is absorbed from the fillings is in the form of elemental mercury, Hg0. This form has high lipid solubility and therefore can cross cell membranes readily including the blood-brain barrier. Intracellularly catalase oxidation converts Hg0 to Hg2+ and this ionic form is responsible for the adverse effects of mercury.7 Mercury clings to sulphur molecules (protein cysteine groups), and sulphur exists in almost every protein in the body, so the effects of mercury toxicity can manifest in any bodily system.7 Concern also exists regarding mercury in conjunction with all the other toxins the body absorbs through food, water and air.
Dentists must recognize the hazards of mercury when working with amalgam. The Ontario Dental Association guide to workplace hazards states11: Dentists working with amalgam should not touch mixed amalgam with their hands. Amalgam that has been mixed but remains unused cannot be thrown into the trash as it is considered toxic waste; it must be stored in a container with a solution that prevents its vapours from contaminating the environment—nevertheless, it is safe to place in one’s mouth.
Should amalgam be banned? Amalgam is a long-lasting, effective filling material that is inexpensive and easy to work with.12 On the other hand, since mercury is the most toxic non-radioactive material on earth, and since it is constantly being released from amalgam, its use should be abandoned.13
One must therefore choose: the dentist must decide if amalgam is to be placed in patients’ mouths, and the patient must decide if they want amalgam in their own mouth or if they have them, that they be removed.
The study of toxicology generally focuses on acute poisoning, not on low, chronic dosing.14 In and of itself, the dose may seem innocuous, but, over time, that dose can take on a whole new effect on the body. Diagnosis of mercury toxicity is difficult as it can mirror many other diseases.7, 14 There is not enough room to mention all the conditions found due to inhalation of mercury vapour based on human studies (animal studies have found numerous additional effects) but the following are just a sample; chest pains, cough, elevated blood pressure, palpitations, inflammation of the oral mucosa occasionally accompanied by excessive salivation, decreased haemoglobin and hematocrit, tremors, muscle pains, excretion of urinary proteins, erythematous and pruritic skin rashes, and may cause either a decrease in immune activity or an autoimmune response depending on the genetic predisposition of the individual.23
Some dentists do not advocate elective removal of amalgam fillings because mercury is released during the removal process. If an amalgam is placed or removed without protective measures (to be discussed below), there is an increase in blood mercury levels for approximately three to four days.15, 16 Elective amalgam removal, therefore, is contraindicated during pregnancy or lactation, since mercury crosses the placental barrier and is expressed in breast milk. The American Dental Association web site states: “To pregnant women who may be concerned about receiving amalgam fillings, Dr. Hujoel says they should know there is little reason for anxiety.”17
If the decision to remove amalgams is taken, precautions are in order. To protect the patient, the tooth to be drilled is isolated with a rubber dam. Some dentists do not use a dam, but try to suction all liquid and debris during the drilling process so that the rest of the mouth is protected. When drilling out the amalgam, copious water spray is used to cool the tip of the drill to minimize vapour production, and a high-volume suction tip removes the water and the debris that is generated. The amalgam should be sectioned so large pieces of the filling can be removed as chunks. Also, a saliva ejector is placed behind the rubber dam to remove vapours and liquids from behind the dam.
Another major concern is the vapour and particulate (sawdust-like particles) ejected at high velocity by the rapidly turning drill that fill the breathing zone.18 During the removal, the patient is protected by an external source of oxygen through a nose piece. For the dentist/dental assistant, either oxygen or a mask fitted with a filter rated for mercury is utilized. Most conscientious dentists have a room filter that constantly cleans the air to ensure that the mercury vapour in the office air is removed.19
The majority of patients do not experience any immediate negative or positive changes after amalgam removal since removal of the filling has not changed the body stores of mercury; rather, the reservoir of mercury has been removed, and chelation/detox is required as the next phase of treatment.
Based on clinical experience some patients feel ill after amalgam removal but it is usually a short lived event. There are rare cases, however, where ill effects have lasted for a number of weeks. Other patients report an improvement almost immediately. This is often explained as being due to the placebo effect but another phenomenon, galvanic reaction, may be occurring.20 Metals in a liquid environment will corrode or rust setting up an electrical current. This can manifest in a metallic taste or a shock in the mouth due to thedischarge of a filling. Some people’s bodies are sensitive to electricity, and this, therefore, affects their physiologic functioning.21 After the fillings are removed, so is the disruptive current, so certain symptoms can disappear.
Everyone must decide if removal is right for him or her as no treatment is without risk. Whenever a tooth is worked on, it experiences trauma. Generally, the tooth recovers quickly, but sometimes the tooth or nerve dies, leading to abscess formation. If this situation arises there are only two possible treatments: root canal or extraction. Leaving an infected tooth in the body is not an option because, 24 hours a day, the immune system must expend energy to try to control the infection. If immune function drops, for whatever reason, flare-ups can occur. Taking homeopathic Arnica or Hypericum after each appointment can stimulate healing and reduce inflammation. Tooth sensitivity to hot or cold may also occur after removal.
Naturopathic doctors use various approaches to detox/chelate metals in the body, often through professional products at their disposal. The focus is the need to get into the tissues and cells and draw out the mercury so the body can eliminate it. If no active treatment is pursued, the mercury can persist in certain tissues for years.7 Mercury is excreted through the urine and stool via the bile.7 Certain practitioners prefer to start treatment aimed at improving liver and kidney function before demanding from these organs the added labour of excreting the mercury through the various detox protocols. Once these organs are stronger, the demands placed on them will not be too onerous. The concern is that, by drawing out the mercury and the toxins that the detox protocol acts on, without the body’s ability to eliminate them we inadvertently re-poison ourselves as the tissues reabsorb the circulating substances. Excreting the mercury through a program can be slow; many months may be required for success as certain tissues have retention half-lives that can last days to years7 and certain chelation protocols are more aggressive than others. Clinical experience reveals that sensitive patients may become ill, so it is prudent to start slowly. If patients can handle the regimen, then the naturopathic doctor can alter the protocol.
According to Health Canada, “Dental amalgam is the single largest source of mercury exposure for average Canadians”; however, the Health Ministry believes that there is not enough evidence to indicate that amalgam is causing illness in the general population.22 A wise individual once said, “I do not need to prove the toxicity of mercury; we have known this for hundreds of years. Rather, you need to prove that mercury amalgam is safe.” (author unknown)
4) Svare,CW; Peterson,LC; Reinhardt,JW; Boyer,DB; Frank,CW; Gay,DD; and Cox,RD. The Effects of Dental Amalgams on Mercury Levels in Expired Air. J Dent Res, 60, 1668-1671, (1981)
5) Patterson,JE;et al. “Mercury In Human Breath From Dental Amalgams.” Bull Environ Contam Toxicol. 34: 459-68, (1985)
7) Fritz,LL; Vimy,MJ; and Summers,AO. “Mercury Exposure From “Silver” Tooth Fillings: Emerging Evidence Questions A Traditional Dental Paradigm.” FASEB J. 9, 504-508, (1995)
8) Smoking Tooth Video. www.youtube.com/watch?v=9ylnQ-T7o1A
9) Vimy,MJ; Lorscheider,FL. “Serial Measurements of Intra-oral Air Mercury: Estimation of Daily Dose From Dental Amalgam.” J Dent Res, 64: 1072-1075, (1985)
10) Mackert,JR. Factors Affecting Estimation of Dental Amalgam Mercury Exposure From Measurements of Mercury Vapour Levels in Intra-oral and Expired Air. J Dent Res, 66: 1775-1780 (1987)
11) Ontario Dental Association Health Hazard Manual pages 24-28, Revised Fall 1995
12) Canadian Dental Association. www.cda-adc.ca/en/oral_health/faqs_resources/faqs/dental_amalgam_faqs.asp#7
14) International Academy of Oral Medicine and Toxicology (IAOMT) www.iaomt.org/articles/files/files193/The%20Cases%20Against%20amalgam.pdf
15) Berglund,A; Molin,M. “Mercury Levels in Plasma and Urine After Removal of All Amalgam Restorations; The Effect of Using Rubber Dams.” Dent Mater 13: 297-304 (1997)
16) Snapp,KR et al. “The Contribution of Dental Amalgam to Hg in Blood.” J Dent Res 68(5): 780-5 (1989)
17) The American Dental Association Posted April 1, 2005. www.ada.org/prof/resources/pubs/adanews/adanewsarticle.asp?articleid=1334
18) Richardson,GM. “Inhalation of Hg-Contaminated Particulate Matter By Dentists: An Overlooked Occupational Risk. Hum Ecol Risk Assess.” 9:1519-1531 (2003)
20) Anderson’s Applied Dental Materials Sixth Edition. John F. McCabe. Blackwell Scientific Publications
23) Center For Disease Control- www.atsdr.cdc.gov/toxprofiles/tp46.pdf (pages 264-283)