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Medical Forum / General / General / November 2004Allowable level of mercury ingestion ?
Twice in one week I've read media articles about mercury / amalgam fillings. Plenty of anecdotes but nothing quantitive. I've an odd bit of filling that dropped out six months ago and decided to do a back-of-envelope calculation. Filling now decidedly black on surface but filing a flat shows silvery metal and no apparent porosity under x30 microscope. Weight 0.58 gm +-0.01gm Volume 0.12cc +-0.02cc from displaced water in a 2mL hypodermic syringe barrel. so Old filling density 0.58/0.12 = 4.8gm/cc Amalgam filling composition 52% Hg, and 48% of Zn,Cu and Ag densities : 13.6,6.9,8.8,10.5 not knowing composition in more detail have taken average of Zn,Cu and Ag so new Amalgam density of 11.3 Loss over say 20 years (assumed, so a big unknown , somewhere between 2 years and 40 years ) =(11.3 - 4.8 ) * (0.58 / 4.8 ) * 0.52 = 0.41 assuming all metals are lost equally, unlikely but I've no info to quantify better. 0.41 gm over 20 years so 20 mg per year If only mercury is totally lost, and in the limit, only leaving the other metals intact then a figure of 30mg per year of ingested mercury No allowance for direct wear, off the filling surfce, also ingested. And only one such filling considered. What is the allowable figure for yearly ingestion of Mercury ? Valid email nutteing@fastmail.....fm (remove 4 of the 5 dots) Ignore any other apparent em address used to post this message - it is defunct due to spam. >Twice in one week I've read media articles about >mercury / amalgam fillings. Plenty of anecdotes [quoted text clipped - 38 lines] >Ignore any other apparent em address used to post this message - >it is defunct due to spam. Just because the mercury is lost doesn't mean that you've had it ingested. There are a few reasons for this. First off, the mercury is released as a vapor, not a liquid. The second is that your body is not designed to absorb mercury that well, so you exhale a lot of it. And everybody except a few vocal few in this newsgroup will tell you that unless you are exceptionally sensitive to mercury, the amount you recieve from your amalgam restorations is not going to be significant. I haven't had any problems yet, every one of my posterior teeth has been restored with amalgam at one point in time or another. Not all of them still exist in my mouth ( replaced them with composite ), but I'm certainly not going to go and have them removed because I'm worried about mercury exposure. -- Adenosine Semi-informed Dental Consumer ? > >Twice in one week I've read media articles about > >mercury / amalgam fillings. Plenty of anecdotes [quoted text clipped - 57 lines] > Adenosine > Semi-informed Dental Consumer ? All very well but I'm trying to get some figures , worst case, or whatever, rather than sentiment. >> about mercury exposure. >> [quoted text clipped - 4 lines] >All very well but I'm trying to get some figures , worst case, >or whatever, rather than sentiment. Methyl mercury is bad (organic mercury) elemental mercury is not bad. You can swallow mercury with no ill effects. You cannot ingest mercury vapor, as this tends to combine with organic molecules ..... Joel M. Eichen DDS > >> about mercury exposure. > >> [quoted text clipped - 10 lines] > > Joel M. Eichen DDS I find it difficult to believe that something with an atomic weight of 200 can be lighter than air. >> >> about mercury exposure. >> >> [quoted text clipped - 13 lines] >I find it difficult to believe that something with an >atomic weight of 200 can be lighter than air. Lighter than air? Nobody is talking about mercury in the mouth making it boyant! I suppose you belive water vapor in the air is a myth too. -- Adenosine Semi-informed Dental Consumer ? > I find it difficult to believe that something with an > atomic weight of 200 can be lighter than air. Mercury exposure from amalgams is primarily through the lungs. Mercury has a significant vapor pressure at room temperature. Elemental mercury is only poorly absorbed through the gut. Steve  SignatureMark & Steven Bornfeld DDS http://www.dentaltwins.com Brooklyn, NY 718-258-5001 > > I find it difficult to believe that something with an > > atomic weight of 200 can be lighter than air. [quoted text clipped - 10 lines] > Brooklyn, NY > 718-258-5001 I eventually found this reference " The US EPA mercury health standard1 for elemental mercury exposure (vapour) is 0.3 micrograms per cubic meter of air (0.3 ug/M3). For the average adult breathing 20 m3 of air per day,2 this amounts to an exposure of 6 micrograms (ug) per day." so 6x365ug = 2.2 mg per year so 10 fillings in my determination would exceed this limit >>>I find it difficult to believe that something with an >>>atomic weight of 200 can be lighter than air. [quoted text clipped - 19 lines] > so 6x365ug = 2.2 mg per year > so 10 fillings in my determination would exceed this limit Remember that, even if we assume your calculation of ingested mercury is accurate, that absorbtion through the gut is poor. Primary absorbtion from amalgam fillings is still through the lungs. Steve > > > I find it difficult to believe that something with an > > > atomic weight of 200 can be lighter than air. [quoted text clipped - 19 lines] > so 6x365ug = 2.2 mg per year > so 10 fillings in my determination would exceed this limit didn't you calculate 20-30 mg per year in you previous post from one filling? Sorry if I misread, I'm going through the posts quickly. Also, keep in mind that there is no guarantee that the release was uniform over time. In fact Hg release rarely is. Therefore the amount per day could have easily been a lot more during an extended period of time during the life of the filling. >> >> about mercury exposure. >> >> [quoted text clipped - 13 lines] >I find it difficult to believe that something with an >atomic weight of 200 can be lighter than air. Me too. When I drop the mercury it always goes up instead of down. AMAZING! >> >No allowance for direct wear, off the filling surfce, also >> >ingested. And only one such filling considered. >> > >> >What is the allowable figure for yearly ingestion of Mercury ? You are omitting the excretion rate of elemental mercury ......... It is not absorbed. There are no mercury receptors in the gut. Joel M. Eichen DDS There is more danger from a bottle of mercury, carelessly handled, dropping, and smashing into a billion little balls. There IS danger from felt workers (literally MAD hatters), from South African gold workers (who use mercury for extraction purposes), and from stupid people who think they can heat old amalgam to reclaim silver and mercury. There have been deaths so beware! JME You can boil the amalgam and recover silver. Don't try this at home Kids/Jan >>> >No allowance for direct wear, off the filling surfce, also >>> >ingested. And only one such filling considered. [quoted text clipped - 17 lines] > > JME >You can boil the amalgam and recover silver. > >Don't try this at home Kids/Jan There have been reports of death from trying. This is a real danger. JOEL **BEWARE** >>>> >No allowance for direct wear, off the filling surfce, also >>>> >ingested. And only one such filling considered. [quoted text clipped - 17 lines] >> >> JME > >Twice in one week I've read media articles about > >mercury / amalgam fillings. Plenty of anecdotes [quoted text clipped - 43 lines] > released as a vapor, not a liquid. The second is that your body is not > designed to absorb mercury that well, so you exhale a lot of it. Right vaporized is less dangerous..... > And everybody except a few vocal few in this newsgroup will tell you > that unless you are exceptionally sensitive to mercury, the amount you > recieve from your amalgam restorations is not going to be significant. That's half the problem with amalgam, half the public are brainwashed like yourself. If you had the ability to read , you would know that many of those vocal critics come from within dentistry or the "establishment" itself. Take John Chewter,who works as a scientist in the dental industry and sees the reality of Hg mixed with bacteria sprayed on dentist office cable lines every day , but is not a dentist himself. I suppose you would characterise him as a nut :), or me, who has grown up in the culture of the FDA. You would also have noticed that the poster claimed nearly .5 gram of leakage from ONE filling, thats a huge amount, but here you are faithfully defending the organization like some kind of simpleton. Are you really that dumb? Seriously.., I'm not trying to be a jerk, I just really would like to know. > I haven't had any problems yet, every one of my posterior teeth has > been restored with amalgam at one point in time or another. Not all of > them still exist in my mouth ( replaced them with composite ), but I'm > certainly not going to go and have them removed because I'm worried > about mercury exposure. No one is saying, rush out and replace amalgam tommorrow if you are healthy. Amalgam removal carries risks as well. >> Just because the mercury is lost doesn't mean that you've had it >> ingested. There are a few reasons for this. First off, the mercury is >> released as a vapor, not a liquid. The second is that your body is not >> designed to absorb mercury that well, so you exhale a lot of it. > >Right vaporized is less dangerous..... Well, he was wondering how much you can swallow, I told him that you can't swallow it because it comes off as vapor. >> And everybody except a few vocal few in this newsgroup will tell you >> that unless you are exceptionally sensitive to mercury, the amount you [quoted text clipped - 10 lines] >suppose you would characterise him as a >nut :), or me, who has grown up in the culture of the FDA. John is a reasonable man (besides, I can't diss anybody who is a fellow computer progger), however, I've never heard HIS arguments against amalgam. I'd have to hear them before I comment on them. >You would also have noticed that the poster claimed nearly .5 gram >of leakage from ONE filling, thats a huge amount, but here you are >faithfully defending the organization like some kind of simpleton. If fillings released that much mercury, even if it took considerable chewing, my fillings would have gotten WAY smaller. I defend the position because I believe the studies toxicologists put out. I also know that I have never met a person who actually had any problems from their amalgams, despite the fact that nearly every single person I know has them. >Are you really that dumb? Seriously.., I'm not trying to be a jerk, >I just really would like to know. Well, I *am* trying to be a jerk. I'm not dumb, it's that I don't try to play a toxicologist. There is obviously a low risk of problems from amalgam, and it's not hard to place (according to most dentists). If it weren't for amalgam I would have never been able to have my teeth restored when I was a child. I think the *even if* there is a *low* risk of problems from amalgam, the health benifits far outweigh the potential problems. >> I haven't had any problems yet, every one of my posterior teeth has >> been restored with amalgam at one point in time or another. Not all of [quoted text clipped - 4 lines] >No one is saying, rush out and replace amalgam tommorrow if you are >healthy. Amalgam removal carries risks as well. Yeah, it makes holes in your pocket. On the plus side it makes your teeth look a lot better. -- Adenosine Semi-informed Dental Consumer ? > =(11.3 - 4.8 ) * (0.58 / 4.8 ) * 0.52 = 0.41 > assuming all metals are lost equally, unlikely but I've [quoted text clipped - 10 lines] > > What is the allowable figure for yearly ingestion of Mercury ? You mean 30 milligrams per years as in 30/1000. Wait! the dentists on the list claim that can't happen! If so the filling surely would have shrunk (according to Fawks)!. Did you see any shrinkage? Yes , that is a lot of mercury, and yes they(dentists) are exposing you and every one else on the planet to horrendous amounts of mercury. In fact, a thermometer which contains about .5 gram is enough to contaminate a lake. But consider this, the mouth is full of bacteria and if it builds up on the surface of the filling or burrows in it can methylize the Hg, which is up to 1000 times more toxic. Hopefully that didn't happen with you but consider that if just 10% of that .4 grams was mehtylized, that is up to 100 times more, targeted to the nervous system. Thanks for taking the time to share the results of a real science experiment, rather than the made up bogus arguments of some of the biggest hucksters on the face of the planet. :) >> =(11.3 - 4.8 ) * (0.58 / 4.8 ) * 0.52 = 0.41 >> assuming all metals are lost equally, unlikely but I've [quoted text clipped - 37 lines] >bogus arguments of some of the biggest hucksters on >the face of the planet. :) What's this? No credable studies linking amalgam restorations to systemic disease? Yeah, same as it has been for a hundred years. Would you please give me the location of your mother's grave? I have some nitrogenous waste I need to get rid of. I have a bunch of amalgam restorations in my mouth, you can see if the extra mercury in the waste causes the grass the gravesite to die. -- Adenosine Semi-informed Dental Consumer ? > >> =(11.3 - 4.8 ) * (0.58 / 4.8 ) * 0.52 = 0.41 > >> assuming all metals are lost equally, unlikely but I've [quoted text clipped - 45 lines] > restorations in my mouth, you can see if the extra mercury in the > waste causes the grass the gravesite to die. Hey listen **ckface. Leave my mom out of it. I post with my real name, so people can see real people get poisoned. You want to take it personal use your real name. Of course your too spineless to do that. You do it again and I'll get your real name from your ISP (making implied threats no matte how vague against family memembers) is against the law or find it myself and be breathing down your neck before you spit. Keep in mind that many other people post with their real name, denists and non-dentists and they have famimly members too ***hole. I insult hidden id's (when people deserve it) but don't make those kind of references to people with real ID's In fact, I think to be on the safe side I will send an email to your ISP. I'll probably know your real name in a day or two. Good job moron, you can't get Hg right and you screwed this up too. Bwahahahahahahahah. You're much more fun than Jan. BTW, have fun finding my actual ISP. -- Adenosine Semi-informed Dental Consumer ? >> =(11.3 - 4.8 ) * (0.58 / 4.8 ) * 0.52 = 0.41 >> assuming all metals are lost equally, unlikely but I've [quoted text clipped - 16 lines] > If so the filling surely would have shrunk (according to > Fawks)!. Did you see any shrinkage? Sounds like an interesting study to do. Intact pieces of amalgam removed. Compare the assays correlated with time in place and see if there is statistical significance. carabelli >>> =(11.3 - 4.8 ) * (0.58 / 4.8 ) * 0.52 = 0.41 >>> assuming all metals are lost equally, unlikely but I've [quoted text clipped - 22 lines] > >carabelli Yeah, but how would you know what alloy was originally placed? Or are you suggesting placing the amalgams, and waiting until they fail? Or placing them, waiting a while, then just taking them out anyway? -- Adenosine Semi-informed Dental Consumer ? *IF* there were this much mercury leaving an amalgam over time, something would have to happen to the restoration. CZ is evidently of the opinion that it mysteriously perculates out of the amalgam and the amalgam miraculously stays the same size and maintains it's integrity in the tooth. *IF* the restoration remains dimensionally stable, then the loss of a substantial portion of it's structure would have some other effect. Is he hinting at porosity? If he is, he hasn't cut very many amalgams with a bur. I have removed amalgams that are anywhere from 6 months to 50 years old. I have been unable to detect any difference in density or strength relating to the age of amalgam. Granted I have not scanned the sectioned amalgams with an electron microscope or measured hardness with a scientific instrument. This would be necessary to measure very small amounts of change. However half a gram is hardly microscopic and would show changes in the qualities of an amalgam over time that could be easily noticed with the magnification and instruments in a dental office. What theories could account for massive mercury leakage yet leave a dimensionally stable, equally dense material (not just for 1-2 years, but even 25 years & up)? I can't come up with one. Fawks >>>=(11.3 - 4.8 ) * (0.58 / 4.8 ) * 0.52 = 0.41 >>>assuming all metals are lost equally, unlikely but I've [quoted text clipped - 22 lines] > > carabelli > *IF* there were this much mercury leaving an amalgam over time, > something would have to happen to the restoration. CZ is evidently of [quoted text clipped - 22 lines] > > Fawks I've posted this supplemental to sci.engr.metallurgy Alloy and amalgam dis-integration question I am aware that brass screws in a marine environment will de-zinc leaving a weak pinkish 'ghost' of the original brass - presumably a porous form of copper. I could well believe that the density of this remnant material may be half the original density of the brass. Could the same marked density reduction either due to galvanic action or vaporisation occur to the mercury component of dental amalgam ? Since starting the thread on sci.med.dentistry copied below I did a bit more exploration. I suspected that filing the filling material may have smeared/disguised any porosity. I had another smaller piece from the same filling and placed in the jaws of some end-snips inside a polythene bag and sheared into two pieces. This showed light-grey , powdery surfaces which when lightly filed showed the silvery colour as before. Viewing under 30x magnification, the grey surfaces, then probably a porous granular material with random tiny black patches, presumably of silver oxide. *************** What they aren't telling you about DNA profiles and what Special Branch don't want you to know. http://www.nutteing2.freeservers.com/dnapr.htm or nutteingd in a search engine Valid email nutteing@fastmail.....fm (remove 4 of the 5 dots) Ignore any other apparent em address used to post this message - it is defunct due to spam. Would that amount to 350 mV or more than that? Joel >Alloy and amalgam dis-integration question > [quoted text clipped - 21 lines] >porous granular material with random tiny black patches, >presumably of silver oxide. That is exactly what I am saying that I have *never* seen happen. I have cut amalgams that were relatively new and very old (40+years). I have never seen a case where the apparent density of the material has been altered. Most of even the degeneration at the margins of a filling are from chipping and cracking. Some measurable corrosion occurs, but nothing of the magnitude that you describe below. It just doesn't happen. BTW, I haven't placed an amalgam since 1985 and have no vested interest in defending the material. Fawks > Alloy and amalgam dis-integration question > [quoted text clipped - 8 lines] > due to galvanic action or vaporisation occur > to the mercury component of dental amalgam ? >That is exactly what I am saying that I have *never* seen happen. >I have cut amalgams that were relatively new and very old (40+years). [quoted text clipped - 7 lines] > >It just doesn't happen. I agree 100% Joel >BTW, I haven't placed an amalgam since 1985 and have no vested interest >in defending the material. [quoted text clipped - 13 lines] >> due to galvanic action or vaporisation occur >> to the mercury component of dental amalgam ? > That is exactly what I am saying that I have *never* seen happen. > I have cut amalgams that were relatively new and very old (40+years). > > I have never seen a case where the apparent density of the material has > been altered. Most of even the degeneration at the margins of a filling > are from chipping and cracking. What technique did you use to measure the density and how many amalgams have you cut open. By the way I emailed an dental expert a while ago and after I referred him to pictures of corroded amalgam, he admitted that 1 in 1000 fillings they study in the field has strange discolorations on the surface they don't understand. I assume that they where in the patients mouth so they couldn't remove them for further study. I already stated that I did not use a scientific instrument to measure density or hardness. However the tactile feel of a handpiece and bur is something where an experienced dentist can easily determine the relative hardness of what is being cut. How many have I cut? 10/week X 50 weeks/year X 25 years = 12,500 (conservative estimate...could be as few as 11,000...could be as many as 18,000 but you get the picture. GOBS of them) Surface discolorations? I haven't seen an amalgam yet that looked good. Different amalgam formulations age differently. Tytin stays pretty shiny (assuming it was ever polished), Dispersalloy gets quite gray, but stays pretty smooth, and I've seen some that are pretty black and pitted *on the surface* (too many brands over the years to keep up with them all). I have seen a few severe bruxers that have worn down their teeth and the amalgams that they got in their teens. That material went somewhere. Most probably swallowed, but that would be about the only people that could possibly have a problem with amalgam exposure (and I haven't seen any of these patients with difficulties). JME, Fawks >>That is exactly what I am saying that I have *never* seen happen. >>I have cut amalgams that were relatively new and very old (40+years). [quoted text clipped - 11 lines] > they where in the patients > mouth so they couldn't remove them for further study. >I already stated that I did not use a scientific instrument to measure >density or hardness. Hardness is best measured by using a ball-pien hammer. > However the tactile feel of a handpiece and bur is >something where an experienced dentist can easily determine the relative >hardness of what is being cut. YUP. HOT KNIFE though soft butter ..... is how I see it. >How many have I cut? 10/week X 50 weeks/year X 25 years = 12,500 >(conservative estimate...could be as few as 11,000...could be as many as [quoted text clipped - 30 lines] >> they where in the patients >> mouth so they couldn't remove them for further study. > I already stated that I did not use a scientific instrument to measure > density or hardness. However the tactile feel of a handpiece and bur is > something where an experienced dentist can easily determine the relative > hardness of what is being cut. Well surely some of those 1000's of amalgams have different percentage of Hg composition. If variations in Hg composition on forumaltion don't cause variations in strength why would the slow loss of Hg necessarily cause detectable changes. It sounds like you think if Hg leaves the filling it will turn to mush. Did you see the post below where it was explained that the phases of an amalgam gradually change during its lifetime freeing up Hg. That is not confined to the surface. > How many have I cut? 10/week X 50 weeks/year X 25 years = 12,500 > (conservative estimate...could be as few as 11,000...could be as many as [quoted text clipped - 5 lines] > stays pretty smooth, and I've seen some that are pretty black and pitted > *on the surface* (too many brands over the years to keep up with them all). And how deep could that go into the filling especially if there are cracks, not to mention the presence of bacteria/fungus which could aid the breaddown with acidic byproducts and then mehtylate the result. Have you ever clincally seen the precscence of bacteria near an area you visually determined to have signifcant breadown. I know in my case the dentist who replaced the amalgam said there was a tremendous amount of decay above the filling up to the root and some people have reported liquified material above the filling. > I have seen a few severe bruxers that have worn down their teeth and the > amalgams that they got in their teens. Well here is where you lose me entirely. If I scratch the surface of a filling large amounts of Hg vapor come off. That is individual Hg atoms. That individual is then exposed to that vapor, not an inert material which is swallowed. I know because I measured the vapor from an amalgam with a Jerome meter once after scratching it. It went sky high in no time. That material went somewhere. > Most probably swallowed, but that would be about the only people that > could possibly have a problem with amalgam exposure (and I haven't seen > any of these patients with difficulties). > > JME, > Fawks I'll discuss more later, have to go > > I already stated that I did not use a scientific instrument to measure > > density or hardness. However the tactile feel of a handpiece and bur is > > something where an experienced dentist can easily determine the relative > > hardness of what is being cut. > That material went somewhere. > > Most probably swallowed, but that would be about the only people that [quoted text clipped - 5 lines] > > I'll discuss more later, have to go How many people go around all day with their mouth open ? > That is exactly what I am saying that I have *never* seen happen. > I have cut amalgams that were relatively new and very old (40+years). [quoted text clipped - 12 lines] > > Fawks This should be measurable: measure the specific gravity of the drilled out pieces of Am and compare that to the SG of new, set Am condensed in a piece of plastic. Then measure the relative compositions of Hg vs other solid parts. Just an idea... YMMV, JMO, SHALOM, the Force Be With You, one cross per prisoner, Cheers, A Dieu. SP SignatureNot a real Addy, yet > > That is exactly what I am saying that I have *never* seen happen. > > I have cut amalgams that were relatively new and very old (40+years). [quoted text clipped - 23 lines] > -- > Not a real Addy, yet I agree. It may be like adding heaps of sugar to coffee or tea that the volume of the liquid increases but not by the amount of the volume of added sugar > *IF* there were this much mercury leaving an amalgam over time, > something would have to happen to the restoration. CZ is evidently of > the opinion that it mysteriously perculates out of the amalgam and the > amalgam miraculously stays the same size and maintains it's integrity > in the tooth. Sure it can, once the structure is set, mercury can leave the amalgam. Suppose you mixed and amalgam with 40 vs 85% mercury. Are you saying one of them wouldn't be stable or fall apart. Granted, I haven't experimentally cut amalgam apart, but other dentists have told me that older restorations do show signs of degredation. As far as you statement (mysteriously perculates out of the amalgam) everyone, even the ADA admits that amalgam has a vapor pressure and continuously leaves the amalgam at a rate of 3-17 ug. It isn't my "imagination". Hg isn't locked into the amlagam, that is WHY it has a vapor pressure. Amalgam is NOT an an alloy which only degrades by acidic corrsion. It's all over the internet, here is a link I found after about 1 minute. http://www.positivehealth.com/permit/Articles/Dentist/dental.htm "The range of mercury exposure levels found in people with amalgam fillings by the World Health Organization Scientific Panel on Mercury was 3 to 70 micrograms per day3, with other medical studies finding up to 200 ug/day in gum chewers or people who grind their teeth6,11,16,17,18" Try working those numbers and calulate how much Hg HAS to leave the amalgam over a 20/30 period > *IF* the restoration remains dimensionally stable, then the loss of > a substantial portion of it's structure would have some other effect. [quoted text clipped - 3 lines] > 50 years old. I have been unable to detect any difference in density or > strength relating to the age of amalgam. Oh come on, someone I know just had an old filling split in half last week. In fact, I did look at it. It seemed to have some zones where the shading was different IIRC. What do you think causes the structural weakness? Do you think steel would split in two after 20 years? Don't forget that the whole point of this thread was an experiment or do you think the poster doesn't know anything either because he's not an "expert". > Granted I have not scanned the sectioned amalgams with an electron > microscope or measured hardness with a scientific instrument. This > would be necessary to measure very small amounts of change. However > half a gram is hardly microscopic and would show changes in the > qualities of an amalgam over time that could be easily noticed with the > magnification and instruments in a dental office. so you have never seen an amalgam look an different than the day it was put it in, internally or on the surface?? Do you think anybody is going to believe that? > What theories could account for massive mercury leakage yet leave a > dimensionally stable, equally dense material (not just for 1-2 years, > but even 25 years & up)? I can't come up with one. As I said above, the same theory that say's an amalgam can be mixed with 30-80% mercury. The Hg sets the matrix, but individual Hg atoms can leave the matrix. Amalgam is a complex and strange substance. Anything that has a vapor pressure at room temperature has a lot of physics going on. >> *IF* there were this much mercury leaving an amalgam over time, >> something would have to happen to the restoration. CZ is evidently of [quoted text clipped - 3 lines] > >Sure it can, once the structure is set, mercury can leave the amalgam. I had one like that. The mercury left the amalgam and then the powder fell out. Joel >Suppose you mixed and amalgam with 40 vs 85% mercury. Are you saying >one of them wouldn't be stable or fall apart. [quoted text clipped - 59 lines] >Anything that has a vapor pressure at room temperature has a lot >of physics going on. > > *IF* there were this much mercury leaving an amalgam over time, > > something would have to happen to the restoration. CZ is evidently of [quoted text clipped - 66 lines] > Anything that has a vapor pressure at room temperature has a lot > of physics going on. I wish someone would repeat my simple experiment. I only have the one available old filling. The internal blck deposits of my sheared piece may be copper sulphide but as the surface goes black in months rather than years I suspect it is silver oxide. +++++++++ What they aren't telling you about DNA profiles and what Special Branch don't want you to know. http://www.nutteing2.freeservers.com/dnapr.htm or nutteingd in a search engine Valid email nutteing@fastmail.....fm (remove 4 of the 5 dots) Ignore any other apparent em address used to post this message - it is defunct due to spam. > I wish someone would repeat my simple > experiment. I only have the one available [quoted text clipped - 3 lines] > as the surface goes black in months rather than > years I suspect it is silver oxide. There is really no reason to re-invent the wheel here. Mechanical and metallurgical properties of amalgam have been studied for a very long time. If you are interested in pursuing this topic in depth, I recommend Skinner's "Science of Dental Materials", by the late Ralph Phillips, published by WB Saunders. With regard to mercury, Phillips writes, "Mercury, per se, does not influence tarnish. In other words, an increased amount of mercury does not necessarily produce greater corrosion. However, restorations with high mercury content result in surface deterioration which then accelerates discoloration. Therefore, technics designed to minimize the final mercury content of the filling lead to superior tarnish resistance by virtue of the smoother surface and marginal areas." He notes that "electron microprobe analysis of tarnished amalgam restorations indicate that the tarnished layer is primarily tin sulfide (Sn2S3) with small amounts of tin oxide present." Steve > +++++++++ > [quoted text clipped - 6 lines] > Ignore any other apparent em address used to post this message - > it is defunct due to spam. SignatureMark & Steven Bornfeld DDS http://www.dentaltwins.com Brooklyn, NY 718-258-5001 Thanks Dr. SB, for an informed scientific reference. You never cease to amaze me with your depth of knowledge. Happy Thanksgiving... ...and I will be expecting my usual check. >> The internal blck deposits of my >> sheared piece may be copper sulphide but [quoted text clipped - 19 lines] > >Steve -- W_B wubbabubbazG@RBAGEyahoo.com Take out the G'RBAGE > Thanks Dr. SB, for an informed scientific reference. > [quoted text clipped - 3 lines] > > ...and I will be expecting my usual check. I just pulled out the durned textbook from the shelf--did you think I was quoting from memory? ;-) Best to you and yours for a happy Thanksgiving! Steve SignatureMark & Steven Bornfeld DDS http://www.dentaltwins.com Brooklyn, NY 718-258-5001 >> Thanks Dr. SB, for an informed scientific reference. >> [quoted text clipped - 6 lines] > I just pulled out the durned textbook from the shelf--did you think I >was quoting from memory? ;-) Well, actually, no. The significant thing is that you knew which book to look in, and knew exactly where that book was. *That* is the true measure of education. > Best to you and yours for a happy Thanksgiving! Thanx and back atcha ! >Steve -- W_B wubbabubbazG@RBAGEyahoo.com Take out the G'RBAGE >I wish someone would repeat my simple >experiment. I only have the one available [quoted text clipped - 3 lines] >as the surface goes black in months rather than >years I suspect it is silver oxide. Ok extract the tooth and send it to the lab. BTW all elemental metals are black when in certain states. Cast gold comes out black, that is why pickling solution is used.. -- W_B wubbabubbazG@RBAGEyahoo.com Take out the G'RBAGE > I wish someone would repeat my simple > experiment. I only have the one available [quoted text clipped - 3 lines] > as the surface goes black in months rather than > years I suspect it is silver oxide. Here is an interesting link. http://www.gbg.bonet.se/bwf/art/instab/micro.html Micro structure. Metallic alloys are seldom homogenous blends of ingredients. If polished and studied under a microscope areas of different compositions can be observed. These are called phases. Phases in dental amalgam can be classified as I/ Alloy powder phases II/ Initial phases III/ Transformation phases When a dental amalgam is prepared a metallic alloy powder is mixed with a certain amount of liquid mercury. This mass hardens resulting in a mix of unaffected alloy powder and new, initial phases. The metal is however not in a state of equilibrium (4). Over the time of years a transformation of the initial phases takes place creating new ones. The result is a mix of alloy, initial and transformation phases. The initial phases contain more mercury than the transformation ones giving free mercury as a result. In the description of the compositions of different phases of amalgam dental researchers almost without exception use a terminology from the field of chemistry. In my opinion this nomenclature gives the false impression that these phases are stable chemical compounds. This is the reason for the unorthodox nomenclature used below. Alloy phases |
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