A recent study in BioMetals offers a scientific indictment on mercury emissions from modern dental amalgam fillings – proving once again that science is on our side.
The study points out what we know, all types of dental amalgams contain mercury, which partly is emitted as mercury vapor. All types of dental amalgams corrode after being placed in the oral cavity.
But then it covers new territory. Modern high copper amalgams exhibit two new traits of increased instability. Firstly, when subjected to wear/polishing, droplets rich in mercury are formed on the surface, showing that mercury is not being strongly bonded to the base or alloy metals. Secondly, high copper amalgams emit substantially larger amounts of mercury vapor than the low copper amalgams used before the 1970s. So let’s tweeze out the key points:
1. The Language of Mercury
It begins with how we talk about mercury.
Dental amalgam fillings are a mixture of 50% mercury and 50% of one or more other metal powders. These alloys can be dissolved into the mercury or, being metal particles, just glued together by mercury. Either way, mercury ends up being the main component of the alloy. Researchers said,
Considering that mercury, not silver, is the dominating metal in the final filling, they should rather be termed mercury fillings.
- The Technical Side of Mercury
Conventionally, mercury amalgams have been promoted as safe and inert. A 2014 study proved this contention false, finding that “almost no amount of amalgam is safe.”
Scientific studies show, no matter how mercury amalgam is mixed or placed, it will emit mercury vapor and corrode in the mouth. Further, mercury amalgam mixes can and do differ significantly. What follows are some former and current “standardized” amalgam contents:
|Conventional Amalgams||Non-gamma 2 Amalgams||Present Standard Amalgams|
|Silver: 65% min.||Silver: 40% min.||Silver: 40% min.|
|Tin: 29% min.||Tin: 32% max.||Tin: 32% max.|
|Copper: 6% min.||Copper: 30% max.||Copper: 30% max|
|Mercury: 3% max.||Mercury: 3% max.||Indium: 5% max|
|Zinc: 2% max.||Zinc: 2% max.||Palladium: 1% max.|
|Zinc: 2% max.|
|Mercury: 3% max.|
In addition, the study points out, some dentists prefer a softer amalgam mix. To achieve this, more mercury is used. Known as the “wet technique,” the excess after packing it into the tooth is removed in the mouth. To get the right consistency, bulk mercury must be used. According to the study,
As a consequence of the ban on the use of bulk mercury in dentistry agreed upon in the Minamata Convention, this technique will be prohibited in the future. However, many manufacturers still provide bulk alloy and mercury.
And yet, another form of amalgam used is “copper amalgam.” Copper amalgam consists of 70% mercury and 30% copper, and some may also contain a variance of 1% of cadmium. Cadmium has been found to be one of the worst metals that can be used in a dental alloy. This amalgam is prepared by heating small pieces of amalgam over an open flame before it’s crushed in a mortar with pestle and cooled for placement. This method of heating results in excessive emissions of mercury.
Children with copper amalgams in all molars could be exposed to as much as 2.3-grams of mercury and 1-gram of copper. Despite this high level of potential exposure, it’s still used in India where it’s considered a “viable alternative by the Indian Dental Academy.”
Not surprising because, after preforming an extensive review of the scientific literature, researchers determined,
There is no consensus on acceptable emissions from dental fillings and there is no awareness of differences in mercury losses from conventional amalgam and non-gamma 2 (ɣ2) amalgams.
- Standardizing Harm
Wondering who takes responsibility for standardizing the toxic slurry packed in mouths? Technically speaking, it’s the International Organization for Standardization (ISO). But as the researchers point out,
ISO standards do not regulate the market for mercury fillings but products already on the market drive the development of these standards.
The ISO’s own website identifies itself as a standard setting body made up of representatives who create documents that provide requirements, specifications, guidelines, or characteristics that can be used consistently to ensure that materials, products, processes and services are fit for their purpose.
- Proof of Instability
Hm: “materials fit for their purpose”? The contention some dentists and dental organizations make is that, when mixed according to a ratio set by the manufacturer, mercury is firmly bound to the alloy in the dental amalgam.
Yet scientists from 1979 to the present have repeatedly documented that the common action of polishing amalgams that contain at least 30% copper, even if done under cold water to minimize heat, produces droplets of mercury on the surface of the tooth. Further, this droplet formation continues for a number of hours after polishing has stopped.
Amalgam’s instability in other clinical situations has also been scientifically noted, with one study noting small “globules” of mercury on the surfaces of fillings from extracted teeth.
These examples not only indicate an increased emission of mercury vapor. According to the authors,
One would expect that droplets rich in mercury found on high copper fillings should have been published and discussed in journals commonly read by dental personnel, especially in an issue involving safety. As far as we can find, this has not happened.
Unfortunately, we cannot find any openly published information/discussion on increased emission of mercury vapor from modern amalgams in any journal commonly read by dental personnel. On the contrary, several big national and international dental organizations have stated that mercury fillings are stable.
An Obvious Conclusion: Mercury Amalgam Fillings are Toxic
Even if all you do is read the abstract of this study, it will be obvious: Mercury amalgam fillings were, are, and ever shall be, toxic. Their toxic nature is why they must be banned.
Image by Ross G. Strachan