Just been to the dentist - it got me thinking about the amazing materials
they use. Rapid setting, no smell or taste. Rock hard in seconds, Good
adhesion, workable.

Does anyone know what the science is behind such materials?

On Jun 9, 1:40 pm, "John" wrote:
Just been to the dentist - it got me thinking about the amazing materials
they use. Rapid setting, no smell or taste. Rock hard in seconds, Good
adhesion, workable.

Does anyone know what the science is behind such materials?

The stuff my dentist uses is UV cure and I'm pretty sure it does
smell.

MBQ

On 9 Jun, 13:40, "John" wrote:

Does anyone know what the science is behind such materials?

There's a pile of vast tomes on the subject here (gf's a hygienist).
Dental materials aren't especially interesting for re-use in non-
dentistry. They're obsessed with non-toxicity, which rules out many
better performing materials. Chances are that if dentists have
something fairly good, there's a poisonous equivalent that's better
and cheaper.

Usually they're UV cure, because it's one good way to avoid the
toxicity of a more chemically-active material. A good dentist will
cure in thin layers, lazy ones pack the whole cavity and then cook it
from the top.

On Mon, 9 Jun 2008 13:40:41 +0100, John wrote:

Does anyone know what the science is behind such materials?

UV cured epoxy I think.

--
Cheers
Dave.

"Dave Liquorice" wrote in message
ll.net...
On Mon, 9 Jun 2008 13:40:41 +0100, John wrote:

Does anyone know what the science is behind such materials?

UV cured epoxy I think.

--
Cheers
Dave.



I have had the UV cured stuff in the past - but this repair was just applied
and was hard in seconds - no application of UV.

Andy Dingley wrote:
On 9 Jun, 13:40, "John" wrote:

Does anyone know what the science is behind such materials?

There's a pile of vast tomes on the subject here (gf's a hygienist).
Dental materials aren't especially interesting for re-use in non-
dentistry. They're obsessed with non-toxicity, which rules out many
better performing materials.

What? Like mercury amalgam? :-)

Also fluoride content (if I understand correctly, this is an intentional
addition to at least some materials) can have its own sorry set of toxic
effects. :-(

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

On 9 Jun, 16:52, Rod wrote:

What? Like mercury amalgam? :-)

I said they were obsessed with talking about it, I didn't say they'd
stopped using the traditional nostrums!

They still use good old Victorian gutta percha for root canal work.


Also fluoride content (if I understand correctly, this is an intentional
addition to at least some materials) can have its own sorry set of toxic
effects. :-(

Not toxic in the way it's used correctly in dentistry though.
Toothpaste is potentially fatal, if the baby chews through a tubeful
of it. The main health problem with fluoride is chronic toxicity from
groundwater.

"John" wrote in message
...

"Dave Liquorice" wrote in message
ll.net...
On Mon, 9 Jun 2008 13:40:41 +0100, John wrote:

Does anyone know what the science is behind such materials?

UV cured epoxy I think.

--
Cheers
Dave.



I have had the UV cured stuff in the past - but this repair was just
applied and was hard in seconds - no application of UV.


I had the whole side fall off one of my molars that had been filled many
years before. Went to see my dentist and he first cleaned up the bad edges,
then attacked it with a micro sand blaster. Yes, that's exactly what it was,
and he said it was to improve the bond between the filler and tooth. He then
mixed up the epoxy stuff (white) and built the tooth back up. It took just a
couple of minutes and I don't think it was UV cured. He then ground a new
'tooth-like' profile on it, and the job was done. Like 10 minutes start to
finish. That was probably 3 years ago, and it still feels and looks exactly
like tooth. As you said, a remarkable material to stand up to the daily
rigours that one of the main chewing teeth has to.

Arfa

Asked my dentist about this a while ago. In fact I don't think the UV cure
is epoxy (but it did have a very long name). I doubt if you'd consider it
apart perhaps from making small models if you saw the price. We use dental
silicone, either the putty or the twin tube stuff, for replicating
engineering defects and that costs an arm and a leg too.

"Owain" wrote in message
...
Arfa Daily wrote:
I had the whole side fall off one of my molars that had been filled many
years before. Went to see my dentist and he first cleaned up the bad
edges, then attacked it with a micro sand blaster. Yes, that's exactly
what it was, and he said it was to improve the bond between the filler
and tooth. He then mixed up the epoxy stuff (white) and built the tooth
back up. It took just a couple of minutes and I don't think it was UV
cured. He then ground a new 'tooth-like' profile on it, and the job was
done. Like 10 minutes start to finish. That was probably 3 years ago, and
it still feels and looks exactly like tooth. As you said, a remarkable
material to stand up to the daily rigours that one of the main chewing
teeth has to.

Sounds like glass ionomer cement

Owain



I'll take your word for that ! So what are the properties of this material ?
Is it used a lot in dental work ? Elsewhere ? Expensive ?

Arfa

Andy Dingley wrote:
On 9 Jun, 16:52, Rod wrote:

What? Like mercury amalgam? :-)

I said they were obsessed with talking about it, I didn't say they'd
stopped using the traditional nostrums!

They still use good old Victorian gutta percha for root canal work.


Also fluoride content (if I understand correctly, this is an intentional
addition to at least some materials) can have its own sorry set of toxic
effects. :-(

Not toxic in the way it's used correctly in dentistry though.
Toothpaste is potentially fatal, if the baby chews through a tubeful
of it. The main health problem with fluoride is chronic toxicity from
groundwater.

Maybe - I do not have information to hand about the relative impacts of
fluoride from different sources. And I do know that in my schooldays, we
were encouraged to swallow toothpaste if had been too slow at swilling
before lights out, or when camping, etc. But I do have this:

Cytotoxicity of dental glass ionomers evaluated using dimethylthiazol
diphenyltetrazolium and neutral red tests.
Lönnroth EC, Dahl JE.

Department of Human Work Sciences, Lule a, University of Technology,
Sweden.

The purpose of this study was to assess the cytotoxicity of some
commonly used glass ionomers. Three chemically cured glass ionomers
(Fuji II, Lining cement, and Ketac Silver) and one light-cured (Fuji II
LC) were tested. Extracts of mixed non-polymerized materials and
polymerized specimens were prepared in accordance with ISO standard
10993-12. The polymerized specimens were cured and placed either
directly in the medium (freshly cured), left for 24 h (aged), or aged
plus ground before being placed in the medium. The cytotoxicity of
extracts was evaluated on mouse fibroblasts (L, 929), using
dimethylthiazol diphenyltetrazolium (MTT) and neutral red (NR) assays.
Further, the concentrations of aluminum, arsenic and lead were analyzed
in aqueous extracts from freshly cured and aged samples, and the
fluoride levels analyzed in aqueous extracts from freshly cured samples.
All extracts except that of non-polymerized Ketac Silver were rated as
severely cytotoxic in both assays. Extracts of polymerized material were
significantly more cytotoxic than extracts of non-polymerized material.
All freshly cured glass ionomers released aluminum and fluoride
concentrations far above what is considered cytotoxic (aluminum 0.2 ppm
and fluoride 20 ppm). Extracts from freshly cured Lining Cement
contained the highest concentrations of aluminum and fluoride (215 ppm
and 112 ppm). Extracts from freshly cured Ketac Silver had the lowest
concentrations of aluminum and fluoride but the highest of lead (100
ppm). It can be concluded that all extracts from non-cured, freshly
cured, and aged glass ionomers contained cytotoxic levels of substances.
Curing did not reduce the toxicity significantly.

http://www.ncbi.nlm.nih.gov/pubmed/11318043


Not sure if formulations have changed, the research has been updated,
etc. since then.

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org