Sciencemadness Discussion Board

Dental Amalgam

j_sum1 - 5-2-2015 at 19:26

I am facing a situation where people I know are freaking out about the toxicity of what is in their teeth and correlating that to everything from suicide risk, psychological issues, neonatal defects, general poor health, weight gain, multiple sclerosis and pretty much everything else under the sun.

I have done some reading and found that mercury toxicity is highly dependent on the form it takes (elemental, metal alloy, vapour, organic, inorganic) and the means of delivery. I also note that inorganic and elemental mercury via the digestive tract is absorbed by the body poorly. There is some evidence of slightly elevated urine and umbilical cord Hg levels under some circumstances of exposure: notably in the first couple of days after fillings have been done while the amalgam is still hardening and/or some may have accidentally been ingested. However the levels of this are extremely small and are below the levels of normal environmental exposure. The key toxicity issue appears to be elemental mercury vapour being inhaled and there being an 80% efficiency in crossing into the blood via the lungs. From there it can form organic mercury compounds (with what efficiency??) and is able to cross the blood-brain barrier. I note that organic mercury is fat soluble and thus affects the brain and other fatty organs and that its mean half life in the human body is 55 days (not sure if that includes the brain though.)
I am aware of bio-accumulation issues that belie somewhat the 55 day half-life figure. I know that fish physiology is different and that bioaccumulation certainly occurs there. I am not so certain what the picture is with humans. There is historical evidence among hatters, cinnibar miners and other users of Hg of toxicological users.

Published literature on the matter appears consistent with the thesis of insignificant exposure via amalgam, below threshold absorption and no statistically determinable detriment. However the literature frequently hedges its bets by saying there is measurable increase in Hg levels in some cases and further toxicological studies are needed to investigate some scenarios.
The literature is also peppered with much pseudoscience and non-scientific articles that are emphatic on the theme of mercury=bad and all means should be employed to get rid of it. Dental literature is noteworthy in this regard. Reading some of these it is clear that there is often a failure to distinguish between the various forms of mercury, differentiate between the physiological pathways or discuss the relevant chemistry. Also there is evidence of poor statistical methodology, cherry-picking of data and much reliance on anecdotal evidence.

I guess my question is an open one – what simple, easily understood, easily verifiable material can I bring to the discussion that will restore some balance and hopefully prevent people I know from freaking out at the thought of mercury in their mouths? Anyone know of any good articles or have good experience working with Hg or experience with heavy metal toxology?

Chemosynthesis, I am paging you. But any others with knowledge also.

Praxichys - 6-2-2015 at 06:59

I have several amalgam fillings, and (most of) my sanity.

I think a lot of that is correlation without causation. People will have psychological issues with or without the mercury. It seems like everyone has some sort of diagnosable psychological issue these days, and the docs are all to happy to supply at $2/pill. Who hasn't had suicidal thoughts at some point or another? Who hasn't experienced some embarrassing weight gain once in their life, or had a headache, or a toothache, etc.?

I am careful because it is clear that lots of mercury causes dementia, but until any substantial evidence surfaces regarding harmful effects at low levels, I am still going to eat fish!

In our effort to find a cure for everything, it seems we are trying to take the "human" out of "being human." As a former writer for SEO/web content, I know just how profitable it is to publish articles full of made-up bullshit "facts" just to generate hype. Sadly, very few in our instantly-gratified society can be bothered to spend 5 minutes to check sources. So, the people eat this garbage for breakfast and then stuff it down the throats of anyone within earshot, generating the ambiguity we now debate.

Maybe you can explain that to them and hopefully not look like another fluoride truther moonbat. But, good luck. For every 500 people who can read the scientific literature, there are 5,000,000 more who read and wholeheartedly believe the Buzzfeed article written by a paid asshole like me... written in such a way as to generate dismissal of genuine data, usually by "uncovering a sinister government scheme" or "things big companies don't want you to know."

As with many subjects, "data" is not collected but rather made by popular vote following mass exposure to a plausible, often fictional, story. I have experienced this frustration many times. Enjoy pissing into the wind.

Edited for a grammar fail.

[Edited on 6-2-2015 by Praxichys]

Chemosynthesis - 6-2-2015 at 09:39

I wish I could give an easy solution. I'm not sure one exists, and this kind of thing has bothered me awhile, as you probably imagine. I will have to give it more thought, but here is where I stand right now.

I don't think it is easy to educate people because the topic of epidemiology and toxicology is such a complex one that the average person won't understand the underlying issues. I offer links, but people don't seem interested in reading.

The cognitive dissonance makes people uncomfortable, and they would need to understand several key points including:

1. Electronic structures differ. Methyl mercury has a different name from elemental Mercury for a reason. Physicochemical properties and bioactivity/metabolism can differ.

2. Amalgams can have various properties. People by and large still cannot seem to fathom concepts such as annealing (an aspect of some unneeded 9/11 controversies, regardless of position).

3. Method of administrations do vary and impact bioavailability. Bioavailability is expressed as a time dependent curve, so you need people to at least comprehend what a value means relative a derivative or an integral. Good luck with that. Inhalation is probably most important for Mercury, and oral administration can have complicated absorption factors I could talk about fruitlessly. It depends on what you need the math to show which brings me to

4. Biological systems are complicated. Explaining a threshold dose, hormesis, or bio accumulation as concepts doesn't get into methodological critiques. There is a well known study where some methyl mercury is correlated with increasing some bird hatchling rates, and experts disagree on whether it tells us anything due to confounding variables. Even without, just assume it tells us something.... Now let's argue what.

I think a lack of education is just fundamental here with the public. You can correlate anything.... With a big enough data set and enough sample groupings, it gets easier to bias data towards your spin. I can even have difficulty in determining what should be investigated despite statistical power/effect sizes, p-values, etc. I take things to another set of eyes I know is both qualified and critical before making too many decisions. The average Joe might not know anyone with those qualifications.

I seriously wish there were more of an outreach for real math and science, with tutoring or YouTube videos, free courseowrk, etc. broken down into ten minute segments for working people and ADD children. My opinion is that adding that in with the appeal of science demos might make a difference, but sadly we can't force people to learn. And like science is totally hard.
I will give it more thought. Maybe when I am in a better mood. Seeing the funding for sham science and watching real scientists lose funding puts me in a bad mood. Especially with all the cheap post docs about.

j_sum1 - 8-2-2015 at 02:38

Thanks both of you for that.
As I have continued reading I have learned more: notably a marked difference between ethyl mercury and methyl mercury and the fact that the properties of the former were at one stage extrapolated from the latter in the absence of any clinical data. this turned out to be a gross overestimation. Half life of methyl mercury in the body I have seen quoted as 50-55 days. The medical effects have been documented and are reasonably well understood. Ethyl mercury has a half-life quoted from 12 days to 18 days. It appears to be far less toxic and less of a legitimate concern.
By rights I should be providing to the thread a list of links that I have been reading. Apologies, I didn't collect them along the way. I have been doing some reading on thimerosal as well s dental mercury. A lot of scaremongering but very little legitimate cause for concern.

It still leaves open the social question of how to deliver the science to someone who considers all scientific information to be tainted by alterior motives and big business conspiracies. (All the people who tell us mercury fillings are safe are in the dental, health or pharmaceutical industries or are scientists who have a vested interest in informing those industries.)

Chemosynthesis - 8-2-2015 at 06:49

Hopefully I was helpful despite being on a depressing rant. One thing to emphasize is that actual patient data is key. Not only do cell lines not mimic the actual metabolism of an animal, but there can be wide variability in animal models. I know quite a few aspects of animal model selection, or some textbook weaknesses in animal models, but if I want animal data, I will collaborate with a specialist.

Even with advances in modeling and data analysis, no toxicokinetics is as valuable as real in vivo, large size samples (double blinded when possible). Metabolic enzymes may have different isoforms, affinities, turnovers, or promiscuities that affect toxicity in an organism. Couple more sources.
PMID: 23401210

DieForelle - 16-3-2015 at 07:38

I seem to be one of the minority around here interested in the various alimentary/medical/nutritional/holistic aspects of chemistry. I briefly worked in big pharma research but found it profoundly, eh, not my cup of tea.

FWIW - and it may not be worth much - I've been concerned about Hg for years. I heard about the Wetterhahn death around the time it happened because one of my chemistry professors had known her. I have a mouth full of amalgam because I had a sweet tooth as a kid. I've had 3 blood tests and one hair test in the past 15 years, the hair test being the most recent, and my mercury has never been high at all, usually near the bottom of the "normal" range. In fact in the hair test, which, I can tell from looking at all the cation traces versus my pattern of mineral supplementation was quite accurate, my mercury level was at the absolute bottom of the limit of detection. Which, I can't remember but was incredibly low. I have always been a egg eater and the cysteine containing proteins supposedly help remove mercury; I also supplemented for a while back in the mid 2000s with 1/2 a bottle of VRP's DMSA product when it came on the market. But my Hg test was low in 2001 before that.

I suspect for the majority of people, eating certain types of fish is orders of magnitude more risky for Hg exposure than dental amalgams. I was never much of a tuna eater but do eat salmon and other fish from time to time. Never liked swordfish or shark.

Given what a microbial smorgasbord our mouths are, I do not rule out the possibility that some organism may eventually evolve to attack amalgam in a way that forms a hazardous organic mercury byproduct; let's see...ehhh...Actinomyces hydrargyrumivorax...but at the rate this world is going, that's currently #7,362,251 on my list of things to worry about.

[Edited on 16-3-2015 by DieForelle]

Chemosynthesis - 16-3-2015 at 14:04

Holistic medicine from a reductionist chemical perspective strikes me as inherently conflicted, as the former attempts to reduce (or eliminate) the necessity of knowledge of the latter. Bridging the gap requires knowledge not just in many fields, but at such a level of specificity as to remain unknown to current science.

If even research specialists have immense hurdles in crossing disciplines, I just don't know how to reach a lay public, hobbyist or not. Oh, DieForelle, did you ever assist/perform any academic research? It's a culture of its own, for better or worse, but can be pretty distinct from corporate environment, despite a bit of a revolving door at the upper echelons and a greater collaborative spirit of the past few years.

aga - 16-3-2015 at 14:29

My mouth has been full of amalgum for 35 years.

Last year i started having them replaced for cosmetic reasons, and the fact that the teeth were cracking due to either age, or expansion of the amalgum.

My body seems to still function. The mind, hmm.

DieForelle - 16-3-2015 at 17:29

Ehhhhh, I'm not exactly sure what you're getting at but that's why I phrased it in a deliberately vague way. (alimentary/medical/nutritional/holistic) I was more talking about "a holistic view of chemistry" or "holistic aspects of chemistry" versus "holistic medicine" which I hope you would agree are two different things. I don't particularly embrace alternative medicine tropes but I'm not automatically skeptical of every last one of them (just most of them), BUT I'm also skeptical of swallowing every so-called proven assertion of "orthodox" medicine either, and would characterize certain sites mentioned in this thread as astroturf ones but I don't really want to start that argument. Everyone is pursuing some kind of agenda, obviously. The problem is, for example, if you'd been running around in the early 2000s saying "Vioxx is bad for you, don't take it" any number of anti-quakery websites would have categorized that as "woo woo" or whatever term they use to denigrate their version of improper thinking, and dismissed it. But, guess what turned out to be true? That Vioxx wasn't safe.

One of the few blogs I read on a semi-regular basis (but by no means always agree with) recently had this useful, I think, post about the shall we say, overall hermeneutics of medical research.

And yes I did real research both in an academic context and (briefly) in the commercial world. Nothing too significant as I never got a graduate degree. My cynicism about both but particularly the latter led me to leave the field of bio or medical research but that would be *way* too much of a digression to go into. (and, actually it's funny I mention P. Greenspun because in the mid-late 90s he had a harrowing yet hilarious webpage concerning how many attempts to follow a career in research or academia go completely awry, despite hard work and the best intentions. That also led me to pursue a career in another area. I also saw it with my own eyes. One of my favorite profs was of molecular genetics but she had a slightly icy personality. I overheard her talking with another professor about how crushed she was when she didn't get tenure. And you just realized...jeez, one can spend 3-4 years somewhere all for nought if you aren't always cheerful with people.)

btw one last clarification: I'd actually had 2 Hg tests, 2 Pb tests (one after I found out my older house was full of lead paint), and then the hair test which would cover both and a slew of other cations. I'm thankfully negative for all the bad stuff.

btw 2: I love when Moms say they don't want any chemicals in their kid's foods. Apparently, they want their kids consuming the pure vacuum of deep space.

[Edited on 17-3-2015 by DieForelle]

j_sum1 - 16-3-2015 at 18:11

It's doubly incongruous (but not quite as funny) when people talk about cleaning products without chemicals.What precisely do they clam to clean? And what with?

(Oh. You got it. It must be a vacuum cleaner.)

Chemosynthesis - 16-3-2015 at 22:49

DieForelleDefinitively stating any dangers of a drug without data behind it (and Vioxx only contributed to a minute fraction of users in post-marketing surveillance, so it's unsurprising to me that it made it to market despite allegations of shady FDA practices) is definitely quackery in my opinion, as it's a huge logical fallacy, regardless of whether it's correct or not. The blog was interesting, though it didn't cite what article it was talking about allergies. Seemed like more Dana Scully syndrome, where a clinical journal was misrepresenting science. Makes me call into question the non-clinical, science educations of the authors. I have definitely seen shady research (knowingly poor animal models to push an agenda, questionable touchups on blots, etc.), including questionably fraudulent practices, though. No one with experience would say it's not there.

I'm sorry your research wasn't enjoyable. I'm not quite old enough to be able to say first hand, but I have heard there has been a decline in the overall environment of scientific research in the past 15 years. I've witnessed some in my time, but I can't quite speak about that time point. I did find quite a difference between for-profit, charitable private, and public research in the times I've spent among them. Maybe others reading will find encouragement from trying a different employer type if they are similarly unhappy.

gregxy - 17-3-2015 at 11:07

A whole industry has evolved around dealing with "hazardous materials".
Lawyers ready and waiting to sue. Contractors ready to re-mediate.
We had a minor water leak a while back. One contractor said it would take
2 weeks and $10,000 to replace the drywall etc (and we would need to
stay in a hotel the whole time). He claimed insurance would pay for it all
so there would be no out of pocket to me. I got a second opinion,
the 2nd guy, who was not a remediation specialist, was able to do everything
in a few hours and charged $700, less than the deductible for the insurance.

Dentists have no doubt discovered there is money to be made replacing older Hg amalgam fillings with new ceramic ones.

aga - 17-3-2015 at 15:16

New dental stuff looks better.

In 30 years it will also need replacing, so if they can get the amalgum replaced by say age 40, they have a good chance of getting paid again for the same job in 30 years.

To be fair, the stuff lasts pretty well considering the environment it has to remain stable in.

Health-wise, there is so much in the modern environment to kill you, pointing the finger at dental fillings is a bit like singling out 1 driver for speeding at the Indy 500/Le Mons.

DieForelle - 17-3-2015 at 18:49

"Definitively stating any dangers of a drug without data behind it..."
Yeah I recognized that would be the interpretation of what I said the way I said it, I sort of wish I'd just let your response be the last on this point. It relies on a lot of fine distinctions and it's probably not worth them time I've already spend on it much less making another post. I never said, for one thing "definitively". Because the whole point of the Greenspun post (or one of them) is "what is definitive" in the medical sciences anyhow? Between the first law of thermodynamics and "our newest pharmaceutical is safe and effective" is a huge practical gulf in terms of actual quality and verifiability of knowledge. I was more imagining this scenario: an alternative medical practitioner, even one with an MD, somehow "notices" "becomes aware of" etc. a lot of negative sequelae of some big pharma blockbuster. Perhaps from an early report in an overseas, lower prestige journal. Furthermore its mode of action also doesn't fit their medical <i>weltanschauung</i>. Conventional medecine labels this person a quack, but when the bodies that approved the drug finally says "oops, we shouldn't have approved it", we (i.e. conventional medicine) are still supposed to discount that the "quack's" viewpoints had any validity. I say, well, the quack might have been onto something...and I say the FDA and its revolving door with the pharma industry is involved in some shady science and quakery itself. Most people would be surprised that Prozac was only 1% more effective than a placebo, but still got approved. BUT...don't get me wrong, I say that very reservedly. I'm not by any means an anti-vaxxer, but I think a degree of skepticism about vaccines is warranted beyond what conventional medicine affords them. I take the side of conventional medicine most of the time, but definitely not all of the time. The problem is most people don't have the educational background to know when to be skeptical. The recent "changing color dress" internet tempest-in-a-teapot illustrated how rampant basic scientific or even logical illiteracy is.

Another big reversal recently is the FDA saying "cholesterol is no longer a nutrient of concern" after telling people to keep it out of their diet for decades. Again, they are somehow given a pass, but a doctor affiliated with the Weston A Price foundation would be labeled a quack by some, even though they've been saying for ages that cholesterol could not possibly be as dangerous as the FDA had tried to tell us it was.

My personal conclusion: there's a lack of nuanced reasoning on both I said, everyone has an incentive to run with their agenda. Less of a lack for orthodox medicine, but potentially far more dangerous there because they have the professional authority to do more damage on their side. People trust and worship doctors...look at how many corny TV shows portray them as some kind of superheroes.

[Edited on 18-3-2015 by DieForelle]

Chemosynthesis - 17-3-2015 at 22:59

Salient points, even though you didn't mention that Prozac is supposed to work in the most severely depressed patients to a statistically significant measure of efficacy. This could be a key to approval as target demographics for severe illness have allowed last resort drugs to be used. The overall statistics are somewhat disturbing. Regulation aside (I consider that another matter, though related), I still consider it more of the Dana Scully syndrome more than anything else. Clinicians rarely have time to read scientific papers, by self-report, and yet clinicians with basically no real research background get worshiped on TV moreso than either non-clinical researchers, those who switched their careers, or dual degree/dual job holders.

Few scientists (MD, PhD or otherwise) that I know in something like toxicology tend to say anything is "bad for you" or "good for you." A misleading cell line or animal model choice, especially when the grant cycle is restarting, perhaps, sadly, but... I don't think outright fraud or as strong of language is typical. Far easier to wave some valid data and a vague statement of potential, and much less risk to ones job and reputation. TV personality clinicians may misrepresent that GRAS, or a full phase 1 study doesn't mean there aren't specific or general toxicities, or that certain subpopulations may have increased risk profiles, etc., and it is a shame that the general public may be conditioned to think their general practitioner understands pharmaceutical research or the in-depth pharmacology of the latest drug to market, but I don't feel that is a reflection on the science itself, or those in the science rather than merely the application.

I think that overall, the catching of various problems and the ease of disallowing drugs to market due to the negative effects on small populations overwhelms the instances of drugs making it to market with known issues, or probably even when a benefit is to an equally small portion of the population. That is a robustness, however flawed the reality is.

craigfire - 22-3-2015 at 20:18

I have a friend, he is melting down dental gold telling me that especially the melting process and its exhaust gas can become a real hazard.

j_sum1 - 22-3-2015 at 20:47

Well, inhalation of Hg fumes is a hazard. No one is denying that. But Hg intermetallics such as those found in amalgam have the Hg tightly bound in a metallic crystal lattice. And those alloys are hard. there is no way appreciable amounts of Hg is getting out without visible erosion. And if it does, the mercury is far more likely to find its way to the digestive tract than to the lungs.

I forget the exact figures, but Hg absorption from the gut into the blood is very low. (2% IIRC)
Hg vapour absorption into the blood via the lungs is much much higher.

Having a filling in your mouth is nowhere near the same thing as melting fillings down for scrap.

craigfire - 23-3-2015 at 20:04

Yes, I understand. Thanks for letting me know.

craigfire - 23-3-2015 at 20:07

Just one question more. What about other dental gold or dental compositions? I have heard about amalgam compositions with gold, silver, platinum or palladium. Have you heard about that. The reason why I ask is that he is thinking about running an experiment with amalgam and precious metals. He wants to find out more about hardness. I would assist him and well I think about hazards for me joining his experiments.

j_sum1 - 23-3-2015 at 20:46

As far as the mercury goes, the rule of thumb would be stay out of the fumes, work with small quantities, research beforehand and run like hell if there is any chance of producing organomercury compounds.

As far as the more exotic amalgams go, you would want to have access to some good analytical equipment otherwise you won't have a clue what is going on. I doubt I could distinguish Pt from Pd by eye in most circumstances.
A typical modern silver amalgam consists of mercury (50%), silver (~22-32% ), tin (~14%), copper (~8%), and other trace metals.
If I recall correctly the copper was substituted for some of the tin some time in the 50s or 60s to make it harder. Amalgams earlier than that had two predominant phases but one of those two was quite brittle. The copper modified that phase to make it tougher.

Au, Pt, Pd amalgams are likely to be a similar complicated mix. And the composition will not be at all standardised. Determining a relationship between the hardness properties and the composition will be no trivial task.
You will want to get good at reading these.

craigfire - 25-3-2015 at 19:37

Wow: I doubt I could distinguish Pt from Pd by eye in most circumstances.

Really, that's possible?

And thank you for the link: that's very useful to me.

[Edited on 26-3-2015 by craigfire]

Chemosynthesis - 25-3-2015 at 19:50

If you want to test hardness, you should look into Rockwell hardness. It is the standard testing method for most metals and materials. Sometimes porosity makes brinnel hardness a measure. I don't know too much about choosing one over another.

craigfire - 25-3-2015 at 19:53

<a href="" onclick="; return false;">Here on this dental gold sell site</a> they say: 80% gold and 16% platinum or 85% gold and 10% platinum or 50% gold, 30% palladium and 18% silver or 70% palladium and 32% silver. What about the amalgam?

I have had a conversation with a doctor - he is recycling dental alloys for his own laboratory. He is just interested in the precious metals (Au, AG, Pt and Pd). He is working with very old dental work remains too. Some of them contain a lot of amalgam - what about the quicksilver? How can he get sure that there are no remains left when he uses the recycled materials as a commodity for new dental works.

This is one of the things my friend wants to find out. Is it really possible - without being a professional refinery - to ensure that all quicksilver remains are really gone?

[Edited on 26-3-2015 by craigfire]

j_sum1 - 25-3-2015 at 21:10

Quote: Originally posted by Chemosynthesis  
If you want to test hardness, you should look into Rockwell hardness. It is the standard testing method for most metals and materials. Sometimes porosity makes brinnel hardness a measure. I don't know too much about choosing one over another.

I have seen Brinnel quoted for dental alloys.
I forget the specific details of both tests (and vickers also). Ultimately, hardness tests are used when tensile tests are impractical. Obtaining the modulus of elasticity and the yield strength and determining the nature of failure is far more valuable than a hardness test anyway. Oh, and there is also the Charpy notch impact test which is an empirical test for toughness.

Tests aside, I think that functionality and stability in situ is the only real qualification. Engineering tests are only valuable to the extent that the data supports the actual situation.

mayko - 27-3-2015 at 15:51

Quote: Originally posted by Chemosynthesis  

1. Electronic structures differ. Methyl mercury has a different name from elemental Mercury for a reason. Physicochemical properties and bioactivity/metabolism can differ.

Genuinely curious; I didn't see it addressed in either of your links. Methyl mercury is created ecologically by the metabolism of various anaerobic bacteria. What if bacterial action inside the tooth generated small but steady amounts of organomercury compounds?

Chemosynthesis - 27-3-2015 at 16:52

That is a really interesting point to bring up. Apparently the mechanism is being speculated a more common than previously thought, but this has been quantified in humans.
DOI: 10.1126/science.1230667 on the thought-to-be-conserved genes involved.

I am doing this at a glance on my phone, so I should probably run it over again, but this is my take right now:
Adult methyl mercury absorption based on salivary production is estimated at 2-3 micrograms of methyl mercury exposure a day, maximum, according to PMC1392265.

EPA limits on methyl mercury take into account human clearance of methyl mercury, and stipulate 0.0004mg/kg daily reference threshold dose, based on maternal blood concentrations and fetal neurological impairment. This helps take into account partitioning to the fetus of a pregnant woman, generally the most susceptible target population.

So unless a pregnant woman happened to weigh less than 10kg or so (being generous), or were supplementing her methyl mercury, even with fillings, I doubt there is much reason for concern for a fetus based on potential total dose exposure of methyl mercury from the fillings themselves, and thus little risk to anyone else. The apparent lack of epidemiological data being a key support for this as well.