Biological detoxification and mercury dental amalgam

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Journal of Dental Research
http://jdr.sagepub.com/content/87/9/800.1
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DOI: 10.1177/154405910808700912
2008 87: 800J DENT RES
Gianpaolo Guzzi and Claudio Minoia
BIOLOGICAL DETOXIFICATION AND MERCURY DENTAL AMALGAM
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International and American Associations for Dental Research

Controlled CliniCal trials and PraCtiCe-
based researCh in dentistry
To the Editor:
In his recent editorial (Mjör, 2008), Ivar Mjör extolled the
virtues of practice-based research, but seemed to suggest that
practice-based settings may not be conducive to the conduct
of randomized clinical trials (RCTs). His point depends on
the perception of a RCT as done to demonstrate efficacy in a
very controlled environment by one or two highly trained and
calibrated expert clinicians who are able to devote extraordinary
time and attention to it. However, there is no reason why RCTs
cannot be used in a practice-based setting to demonstrate
effectiveness (the outcome in practice). One would focus on the
intervention as used in practice, with simple clinical outcomes.
Variations of participating dentists in background and skill
would be present, but are part of the background noise. If the
outcome is not significantly greater than the background noise,
then it won’t have any impact on practice.
An example is an upcoming RCT in NW PRECEDENT
in which we will compare mineral trioxide aggregate (MTA)
and calcium hydroxide as pulp-capping materials in member
practices. Each dentist will be randomized to use only one
of the two for all pulp caps needed over a specified period.
Outcomes after two years will be whether the treated tooth
required endodontic treatment or extraction, or if it remains
vital. This addresses the kind of “identified” and ”recurring”
clinical problem Dr. Mjör suggests should be pursued in dental
practice-based research networks, but does so with a RCT
design that should produce the highest-quality evidence of
effectiveness.
— Timothy A. DeRouen
Executive Associate Dean for Research and Academic Affairs, University
of Washington, Seattle, USA
— Jack Ferracane
Chairman, Department of Restorative Dentistry, Oregon Health and Science
University, Portland, USA
Co-Directors, Northwest PRECEDENT Dental Practice Based Research
Network
reFerenCe
Mjör IA (2008). Controlled clinical trials and practice-based research in
dentistry (guest editorial). J Dent Res 87:605.
The author replies:
Thank you for the opportunity to comment on the Letter
to the Editor from Drs. DeRouen and Ferracane at the NW
PRECEDENT practice-based network. I am pleased to note
that we agree that RCTs can be done in practice-based research
(P-BR), as expressed in my Guest Editorial. The network’s
pulp study referred to is an example of a RCT design carried
biologiCal detoxiFiCation and MerCury
dental aMalgaM
To the Editor:
In their randomized controlled trial, Melchart et al. (2008)
addressed the important issue of how to treat health conditions
associated with amalgam.
We wish to raise two points. In the group termed “removal-
plus group”, a “biological detoxification” therapy was used to
treat patients’ symptoms consistent with exposure to amalgam.
Me lchart and co -workers see m u naware that s el enium
selenite—which was chosen in their trial—while an essential
element, is also a toxic compound (Guzzi and La Porta, 2008).
We were surprised that the authors chose to supplement the
“removal-plus group” with inorganic sodium selenite, usually
used in experimental studies (Tandon et al., 1986).
Because of the “biological detoxification”, we would expect
to see organic selenium (selenomethionine, selenocysteine, and
selenium-yeast) instead of sodium selenite in the supplemented
group. Selenium supplementation decreases the excretion of
mercury, and the formation of mercury selenide (Hg-Se) may
become a secondary source of mercury, worsening the retention
toxicity owing to mercury (Tandon et al., 1986; Agarwal and
Behari, 2007). Furthermore, selenium may increase brain levels
of methyl mercury (Tandon et al., 1986), which is present in the
saliva in individuals with amalgam.
Selenium is very far from being safe for persons exposed to
mercury.
In addition, neither intravenous vitamin C (in a clinical
study) (Dirks et al., 1994) nor ascorbate (in an animal model)
(Guzzi and La Porta, 2008) has been shown to be beneficial in
removing mercury from human tissues. We believe that there is
no evidence that biological detoxification may have benefit in
persons with symptoms associated with exposure to amalgam.
The management of mercury body burden due to amalgam
remains complete removal of dental amalgam fillings.
— Gianpaolo Guzzi1 & Claudio Minoia2
1Italian Association for Metals and Biocompatibility Research, (AIRMEB),
Via F. Sforza, 15, 20122 Milan, Italy, gianpaolo_guzzi@fastwebnet.it
2Laboratory of Environmental, and Toxicology Testing “S. Maugeri”-
IRCCS, Pavia, Italy
reFerenCes
Agarwal R, Behari JR (2007). Role of selenium in mercury intoxication in
mice. Ind Health 45:388-395.
Dirks MJ, Davis DR, Cheraskin E, Jackson JA (1994). Mercury excretion
and intravenous ascorbic acid. Arch Environ Health 49:49-52.
Guzzi G, La Porta CA (2008). Molecular mechanisms triggered by mercury.
Toxicology 244:1-12.
Melchart D, Vogt S, Kohler W, Streng A, Weidenhammer W, Kremers L,
et al. (2008). Treatment of health complaints attributed to amalgam. J
Dent Res 87:349-353.
Tandon SK, Magos L, Webb M (1986). The stimulation and inhibition of
the exhalation of volatile selenium. Biochem Pharmacol 35:2763-2766.
J Dent Res 87(9):800-801, 2008
letters to the editor
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International and American Associations for Dental Research

J Dent Res 87(9) 2008 Letters to the Editor 801
out in practice.
However, there is more to P-BR than training clinicians
to do RCTs in their practices, and that is to identify recurring
problems encountered in practice. Many examples can be
quoted. I will mention two. When resin-based materials came
into common use 30-40 years ago, marginal staining was a
major problem. As the problem was identified, it was solved by
introducing acid etching as part of the restorative procedure.
The clinical diagnosis of secondary (recurrent) caries is a
frequent reason for replacement of restorations. It dates back
a century, when G.V. Black identified it as a major problem
associated with amalgam restorations. Since P-BR has shown
this diagnosis to be the most common reason for replacement
of all types of restorations, it calls for research to solve the
recurring problem. Progress has been made, and more needs to
be done.
I maintain that a recurring clinical problem must be
identified or it will not be resolved. It is unlikely that P-BR will
solve the problem per se, but it will allow the dental research
community to focus on problems relevant to dental practice.
— Ivar A. Mjör, Professor Emeritus
Academy 100 Eminent Scholar, College of Dentistry, University of Florida,
PO Box 100415, Gainesville, FL 32610, USA
note to readers:
In future issues, Letters to the Editor will
appear only in the online Journal of Dental
Research. The JDR can be found online at
http://jdr.iadrjournals.org
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