The International Oral Lichen Planus Support Group2 receives many emails and letters from patients who constantly search for causes related to their oral lichen planus. Many patients wonder if mercury leakage is causing their disorder or making it worse. And, to add to the confusion, conclusions in pathology reports often indicate a diagnosis of what is termed “a lichenoid-type reaction.”3 Lichen planus usually affects an older population and most patients have multiple amalgam restorations since that has been the choice of restorative materials during their lifetime. We often are asked, “If I have oral lichen planus, should I remove my amalgams because of questionable mercury safety and potential mercury leakage? And, “Do you think this is causing my lichen planus?”
The lasting quality of amalgam is not a debate. However, when amalgam leaks or when the dental material is removed, mercury vapor is released, in the form of elemental Hgo, and is absorbed by the lungs and the body (FDA, 2015).28 High levels have effects on the lungs, kidneys, central nervous system and brain. Mercury from dental amalgam (Hgo) and other sources (e.g., fish), in the form of CH3Hg, occur in many individuals and these forms are bio accumulative.
Mercury is also released in extremely small amounts from dental amalgams while normal functions are performed such as chewing, eating, brushing, grinding of teeth and even polishing teeth in the dental office.
In a 2017 published study, Bengtsson & Hylander wrote a paper titled, “Increased mercury emissions from modern dental amalgams” that evaluated the emissions of mercury and vapor emissions in modern high copper amalgams used in Europe and the United States. The authors cite that amalgams are a mixture of mercury and one or more other metal powders referred to as the alloy (silver, tin, copper or zinc). The mixing ratio is approximately 50/50. The mixture of the two components is termed, dental amalgam. Amalgams may be either low or high copper content. The high non-y2 amalgams introduced in the 1970’s emit high amounts of mercury vapors. These newer amalgams with high copper were developed for their mechanical strength and corrosion resistance. The study authors challenged the assumption that mercury in dental amalgam is firmly bonded to the alloy, due to the mercury-rich droplets found on the surface of the newer high copper dental amalgams. When high copper amalgams are stimulated/polished, mercury-rich droplets are visible using a SEM microscope (Figure 1).
In previous studies, the low copper amalgams (prior to the 1970’s), also referred to as the (y2-amalgams), were found to emit less mercury than the newer, high copper amalgams (non-y2 amalgams). The emitted mercury vapor in high copper amalgams emitted 3-43 times as much mercury vapor than the original lower copper amalgams used before 1970’s. Depending upon the type and mixture, the high copper amalgams (non-y2-amalgams) had the highest emission of mercury vapors. The authors conclude that chewing, polishing or temperature changes related to hot foods may stimulate higher emission of mercury vapor and over time, these may amount to more cumulative exposure.
According to the FDA, “Some individuals have an allergy or sensitivity to mercury or the other components of dental amalgam (such as silver, copper, or tin). Dental amalgam might cause these individuals to develop oral lesions or other contact reactions that can affect the skin and the mucous membranes. If a patient is allergic to any of the metals in dental amalgam, this patient would not be a good candidate for amalgam. Other treatment options should be discussed with the patient. Positions from the ADA (2016) state that there is no association with Alzheimer’s Disease, Parkinson’s Disease, Lupus, Multiple Sclerosis and other degenerative diseases that have been suggested in past articles.3 The statement cites multiple studies from reputable journals and known organisations noting a disconnection to these disease states.
Some patients ask if all amalgams should be replaced and if the mercury leakage that may occur in older restorations is contributing to oral tissue ulcerations such as oral lichen planus. Oral tissue that is in direct contact with an amalgam restoration or perhaps a metal (gold) crown may exhibit what is called a “lichenoid” reaction. A dermatologist can perform what is termed “Patch Testing” and other tests to determine if there is evidence of metal sensitivity. Reports of amalgam removal that is linked to tissue reaction has been known for many years. Sometimes the tissue contacting the metals will improve upon removal of the amalgam or gold crown and the clinician may conclude that there was product sensitivity when improvement results after removal. Recent studies by Tiwari, et al. 201814 cited a high rate of clinical improvement (95%) of patients’ reduction of lichen planus upon the removal of existing dental restorations. Bjorkman et al., 201711 reported an improvement in overall health complaints in a group of patients five years after removal of amalgam restorations. The patch tests indicated allergy sensitivity to gold, mercury, nickel, copper, potassium dichromate and methylhydroquinone. Even when biopsied and viewed under a microscope, the diagnosis is often unclear and may appear as lichen planus. Some pathologists will diagnose this as “Lichenoid Mucositis” or others may indicate just “a lichenoid reaction.” Documenting any tissue changes by making before and after images of the tissue will usually answer this question. A dermatologist can determine if metal sensitivity may be an issue and conduct epicutaneous patch testing. Some dental facilities who engage a dermatologist may include this procedure as part of a normal protocol when there is any question about the etiology and its relationship to oral sensitivity.
If a patient requires a restoration to be replaced, the dental provider will most likely use a newer material to replace an amalgam. If the restoration is broken or extremely defective, amalgam leakage could be a concern and there is a need to address this issue by replacing the restoration. Sometimes older amalgams will seal themselves – this is one of the benefits of the amalgam materials – or they may get decay under the amalgam. So, radiographs and clinical evaluation are always necessary to determine the need for replacing a possibly defective amalgam restoration.
A recent publication by the Canadian Medical Association 201612 suggests that physicians ask some key questions of patients who are concerned about mercury and are considering removal of their restorations. The physician would want to ask the patient about the number and integrity of the patient’s restorations and his/her chewing habits including any bruxism. Questions concerning occupational exposure to mercury should also be addressed such as whether the person has worked around processes involving mercury. Inhalation and exposure to mercury is a concern as well. Fluorescent light bulbs (broken) is of concern and a source of Hgo. Some vaccines are a concern such as thimerosal, which is partly metabolised into ethylmercury. Again, all exposure is cumulative, and some individuals will have more substantial accumulation than others. Some physicians do special tests for this in physical examinations when warranted.
Recent studies, 2017, and results from a five-year follow-up of patients who had high mercury concentration in their urine before amalgam removal were examined again at a later date. After removal of the amalgams, the patients reported improved health conditions. The study was considered subjective and based on patient reported data in a small study population. Other studies report an overall health improvement and believe there is a systemic allergenic/irritant potential in some patients13 (Sharma, et al. 2015). Recent publications by Tiwari, et al. 2018,14 reported improvement in lichen planus in a group of 23 patients with improvement of 19 patients when the amalgam restorations were removed and complete remission in 11 patients. Removal of amalgam material amounts to several considerations: With any amalgam removal, consideration of the patient includes the potential to swallow particles, breathing mercury vapors into the lungs and the release of Hg0 into the operatory.
The FDA (2015) suggests that the developing neurological systems in fetuses and young children may be more sensitive to the neurotoxic effects of mercury vapor. Therefore, pregnant women and young children may be more at risk. This, of course, would be a concern for dental professionals who work around mercury vapors in the dental office and especially those who may be pregnant or considering a pregnancy in the near future. Recent studies by Cariccio, et al. 201827 discuss the involvement of mercury in neuronal damage in neurodegenerative diseases.
“Dental amalgam can emit mercury vapor. Mercury vapor, being highly volatile and lipid soluble, can cross the blood-brain barrier and the lipid cell membranes and can be accumulated into the cells in its inorganic forms. Methylmercury, though not found in dental amalgam, can pass through blood-brain and placental barriers, causing serious damage in the central nervous system.”27
Other Mercury Sources:
The FDA and EPA has suggested that consuming fish (CH3Hg) with potentially higher mercury levels should be avoided. Fish such as tilefish from the Gulf of Mexico; shark; swordfish; orange roughy; bigeye tuna; marlin; and king mackerel are known to have higher levels of mercury. Generally, the larger fish are more of a concern. Lower levels of mercury are found in seafood such as: shrimp, pollock, salmon, canned light tuna, tilapia, catfish, and cod. The FDA states that mercury from dental amalgam and other sources (e.g., fish) is bio accumulative in organs. Therefore, limiting the exposure to added mercury sources is optimal. This could be a prime consideration for patients who have exposure to mercury or those who have multiple amalgam restorations.