There are three kinds of people in the world—those who understand mathematics, and those who don’t. This joke, which a buddy of mine told me a few years ago, got me thinking about how science and the scientific method are used (or not used) and abused within clinical dentistry.
Many over-the-counter (OTC) products have never gotten within a thousand miles of randomized clinical trials (RCTs). Food and Drug Administration (FDA) approval depends upon demonstrations of safety and efficacy, which are determined through RCTs.
The licensed promoters of OTC products do not necessarily need to demonstrate their efficacy. The Federal Trade Commission (FTC) regulates the truth in their advertising. These companies can not overtly lie about the efficacy of their products.
OTC products typically don’t need to go through such a rigorous and expensive process, which may show that they are not efficacious anyway. The advertising for OTC products may be misleading, but it can’t be an outright lie.
This is why the pejorative term “snake oil” could be appropriate for some of these products. Evidently, the public is okay with this situation, or it would be politically expedient to change government regulations, or what some call red tape.
In the Real World
I was director of a dental school’s continuing dental education (CDE) program from 2007 through 2019. During that time, I set up many CDE programs for dentists who had been investigated by various state dental boards and who had signed a legal consent decree in which they agreed to successfully complete various CDE courses to maintain valid state dental licensure.
Mostly, the courses required by these decrees focused on clinical dentistry such as periodontal diagnosis, patient records, pharmacotherapeutics, and similar issues. However, I also came across issues related to holistic and homeopathic dentistry.
For instance, I was not familiar with the concept of autonomic response testing (ART). ART is the evaluation of the strength of muscle effort increasing or diminishing when the patient is exposed to various substances (therapeutics).1,2
I also was introduced to other dental holistic and homeopathic practices such as bioelectric energy stress evaluations, as well as therapeutic practices such as sinus injections, detoxification with chlorella and garlic, and IV injections of vitamin D, procaine, echinacea, insulin, mucokehl, protamine, and zinc.
I was already familiar with alternative dentistry organizations and the promotion of “biologic dentistry,” or the practice of dentistry using natural therapies. Organizations that promote biologic dentistry are potentially problematic for dentists with respect to chronic illnesses and disease prevention, optimal performance, non-invasive diagnosis, and assessment as well as understanding the role that emotions play in illness.
I have particular concern with regard to alternative dentistry’s views concerning vaccines and autism.3,4 Themerosal is a mercury compound that used to be utilized as a preservative in vaccines, but it was removed years ago due to concerns about its safety. Unfortunately, because of the supposed connection between vaccines and autism, many individuals presently refuse vaccination for themselves and for their children.
The connection between mercury, vaccines, and autism has been completely debunked by science, but the concept still perseveres as a great conspiracy.5,6 It appears that concerns regarding mercury have been the lynch pin for holistic and homeopathic dentistry, much of which was established over the concern about dental amalgams.
Toxicology/pharmacology is another area of science important for clinicians to comprehend. One of the basic concepts of toxicology/pharmacology is the dose response curve. Even very strong poisons require a minimal dose to cause injury.
The issue of mercury toxicology with reference to dental amalgam restorations is a case in point with respect to the perversion of science. Based upon science, the ADA has continuously reported that dental amalgam restorations are safe and efficacious.
“Dental amalgam is considered a safe, affordable and durable material that has been used to restore the teeth of more than 100 million Americans. It contains a mixture of metals such as silver, copper and tin, in addition to mercury, which binds these components into a hard, stable and safe substance. Dental amalgam has been studied and reviewed extensively, and has established a record of safety and effectiveness,” the ADA has said.7
Compared to composite dental restorations, amalgam restorations last longer. They also are cheaper, easier and quicker to place, and kinder to oral tissues, though they certainly are not as cosmetic. Although mercury is known as a neurotoxin, scientific inquiry has continuously demonstrated that, within dental amalgam restorations, mercury is not a health concern for dental patients.8-15
It is important for clinical dentists to be able to read a journal article and determine the validity of the science. Many clinical dentists are unable to evaluate published clinical studies, which may account for how many dentists have taken up alternative dentistry.
For years, I have used a particular published journal article to demonstrate to residents in dental graduate programs how a biased and perverted study can get published by a very credible journal.16
The non-randomized study examined 47 medical students with amalgam restorations and 14 medical students without amalgam restorations. This study was biased from the beginning.
Mercury is liberated as a vapor from alloys through heating. Pre-chewing levels of mercury vapor were measured in the mouth of each subject. Then, subjects were provided with one stick of sugarless gum and instructed to chew it for three minutes at a pace of two beats per second by following the beat of a metronome to model eating.
Obviously, the pace was chosen to heat up the dental restorations and, therefore, liberate elemental mercury. It was not a model comparable to how mercury would be released in a physiologic model of chewing food.
After the three minutes were up, the researchers analyzed the levels of mercury vapor in the mouth as well as the levels of mercury in each subject’s blood. The subjects with amalgam restorations had a level of 0.7 ng/ml in their blood, while the subjects without amalgam had 0.3 ng/ml. There was a standard deviation of 0.3, and the p value was 0.01.
The groups were unequal in size, though. Also, there was significant overlap of the means and standard deviations. One doesn’t need to be a statistician to understand that something is rotten in Denmark.
Yet this study is quoted within the dental literature and in anti-amalgam alternative dentistry literature to demonstrate that mercury exposure is a risk for patients with dental amalgam restorations.17-19
Amalgams Versus Composites
Certainly, composite dental restorations are not snake oil. Composites are excellent restorative materials and continue to improve. But the attack against dental amalgam restoration toxicology and science has spurred problematic responses by alternative dentists.
The ADA and other dental organizations need to advise dental patients about the science of dentistry and toxicology. The views of many practitioners within the alternative, holistic, and homeopathic dental communities have poisoned the public’s understanding of oral health concerns by disregarding science and scientific principles.
- Hammond C, Lieberman JA. Unproven Diagnostic Tests for Food Allergy. Immunol Allergy Clin North Am 2018;38(1):153-163.
- Beyer K, Teuber SS. Food allergy diagnostics: scientific and unproven procedures. Curr Opin Allergy Clin Immunol 2005;5(3):261-266.
- Argou-Cardozo I, Martin JAC, Zeidan-Chulia F. Dental Amalgam fillings and the use of echnological devices as an environmental factor: Updating the cumulative mercury exposure-based hypothesis of autism. Eur J Dent 2017;11(4):569-570.
- Stehr-Green P, Tull P, Stellfeld M, Mortenson P-B, Simpson D. Autism and Thimerosal-Containing Vaccines – Lack of consistent evidence for an association. Am J Prev Med 2003;25(2):101-106.
- Baker JP, Mercury, Vaccines, and Autism: One controversy, three histories. Am J Public Health 2008:98:244-253.
- Tomeny TS, Vargo CJ, El-Toukhy S. Geographic and Demographic Correlates of Autism-Related Anti-Vaccine Beliefs on Twitter, 2009-15. Soc Sci Med 2017;191:168-175.
- www.ada.org › ada-positions-policies-and-statements
- Brown RS. The Chicken Little syndrome. J Amer Coll Dent 2007;73:25-29.
- Brown RS. Dental amalgam and mercury toxicity. J Greater Houst Dent Soc 1990;61:15-16. 15. Brown RS, Hays GL, Lusk SS. A possible instance of hypersensitivity to Mercury amalgam placement: A case report. J Greater Houst Dent Soc 1993;64:8-10.)
- Wahl MJ. Amalgam-Resurrection and redemption. Part 2: The medical lmythology of anti-amalgam. Quintessence Int 2001;32:696-710.
- Wahl MJ. Amalgam-Resurrection and redemption Part 1: The clinical and legal mythology of anti-amalgam. Quintessence Int 2001;32(7):525-535.)
- Brownawell AM, Berent S, Brent RL, et al. The potential adverse health effects of dental amalgam. Toxicol Rev 2005;24(1):1-10.
- Clarkson TW, Magos L, Myers GJ. The toxicology of mercury – Current exposures and clinical manifestations. N Engl J Med. 2003;349:1731-7.
- Bellinger DC, Trachtenberg F, Barregard L, et al. Neuropsychological and renal effects of dental amalgam in children: a randomized clinical trial. JAMA 2006;295(15):1775-1783.
- Abraham JE, Svare CW, Frank CW. The effect of dental amalgam restorations on blood Mercury levels. J Dent Res 1984;63(1):71-73.
- Vimy MJ, Lorscheider FL. Intra-oral air mercury released from dental amalgam. J Dent Res 1985;64:1069-1071.
- Skare I, Bergstrom T, Engqvist A, Weiner JA. Mercury exposure of different origins among dentists and dental nurses. Scand J Work Environ Health 1990;16(5):340-347.
- Mackert JR. Dental amalgam and mercury. J Am Dent Assoc 1991;122(8):54-61.
- Mackert JR, Berglund. Mercury exposure from dental amalgam fillings. Absorbed dose and potential for adverse health effects. Crit Rev Oral Biol Med 1997;8:410-436.
Dr. Brown is a clinical associate professor in the Department of Otolaryngology at Georgetown University Medical Center. He also is a professor emeritus with the Department of Oral Diagnosis & Radiology at the Howard University College of Dentistry. He can be reached at firstname.lastname@example.org or at email@example.com.