How safe are cobalt-chromium and nickel-chromium alloys used in dental implants (porcelain fused metal)? IARC groups nickel and cobalt metals in group 2B and chromium in group 3 (hexavalent chromium is group 1!). But what is the likelihood of these metals leaching from implants and affecting the body? Aren't some of these metals already used for kitchenware (stainless steel vessels for instance contain chromium) and in industrial containers used for food processing? Is the risk much higher when these metals (not their more toxic compounds/salts though) are present in mouth when compared to their being used for food storage or cooking?

  • $\begingroup$ I would guess these are steel-alloys, right? $\endgroup$ – Chris Sep 26 '14 at 19:09
  • $\begingroup$ @MattDMo you can convert this comment to an answer. $\endgroup$ – WYSIWYG Jan 14 '15 at 8:52

Alloys have completely different chemical properties than their component elements. Elemental mercury is liquid, and is toxic, but when alloyed into amalgam with silver, tin, and some other elements it is perfectly safe, and has been used in dental fillings for a very long time with no negative effects. The same is true of cobalt and chromium alloys - they are chemically bonded to the other elements in the alloy, making a new molecule, and cannot "leach out" without the chemical bonds being broken, which cannot happen in the mouth or at standard cooking temperatures. Hence, they are safe for food prep and for fillings/implants.

  • $\begingroup$ But I have read reports in health columns warning that amalgams with some heavy metals can be dangerous in the long term since some tiny amounts of these elements will inevitably enter bloodstream occasionally, accumulate in some vital organs and hereby have the potential to cause chronic illnesses. I even saw a somewhat similar thing mentioned in a health awareness book written by a neurologist - that certain tooth fillings are suspected to be the cause of some degenerative neurological conditions. Are these studies flawed? $\endgroup$ – so2 Apr 10 '15 at 18:47
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    $\begingroup$ @so2 Please give some references to these "health columns" and the "health awareness book". Anyone can write anything they want, that doesn't mean it's true, or supported by peer-reviewed research. $\endgroup$ – MattDMo Apr 10 '15 at 18:49
  • $\begingroup$ Here is one of the many websites that mention amalgams can be dangerous: curezone.org/diseases/cancer/cancer_dental_risk.asp. Many of these websites mention names of doctors and medical institutions. I agree that the internet has a lot of misleading information and I also find an increase in the amount of health news that we cannot use, but was concerned about dental implants thing because I have also read articles in reputed newspapers that mention health hazards of heavy metal contamination in general, though they were not in the context of dental implants. $\endgroup$ – so2 Apr 15 '15 at 15:36
  • $\begingroup$ @so2 that page is full of random quotes from dentists, unsourced claims, and links to other unverified websites, without a single citation to reputable peer-reviewed literature or actual evidence - it's scare-mongering. Just because a doctor associated with a medical institution says something, doesn't mean it's true - you need evidence. Yes, heavy metals on their own can be highly toxic. However, as I described in my answer, amalgam is an alloy of different elements, and its chemical properties are entirely separate from the properties of the individual components that make it up. $\endgroup$ – MattDMo Apr 15 '15 at 15:57
  • $\begingroup$ Here is another one that cautions against using aluminum foils to store food while clearly stating that there is no strong scientific evidence showing these practices to be harmful to health: whfoods.com/genpage.php?tname=newtip&dbid=8. It also cites some studies. Atleast it provides a more balanced view & is not bent of creating a scare. Would you mind updating your answer to state that no scientific study has given a conclusive evidence of long-term harmful effects of metallic dental implants, or if a study has proven they are perfectly safe, provide a link? Thanks! $\endgroup$ – so2 Apr 15 '15 at 18:22

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