How do amalgam fillings work?

How do amalgam fillings work?

Just out of curiousity, how do amalgam fillings work? Composite fillings
need some sort of adhesive. How do amalgams adhere to the teeth?

Re: How do amalgam fillings work?

Robert wrote:
> Just out of curiousity, how do amalgam fillings work? Composite fillings
> need some sort of adhesive. How do amalgams adhere to the teeth?
>
>


When I was in school we in fact did NOT use bonding techniques with
composite. Bonding was discovered in the mid 1950s, but I don't know if
the early studies used unfilled resins as adhesives. Bonding can be
done without a bonding agent, but it's much less effective.
Naturally, resin fillings done without bonding were a pretty dicey
proposition because of the amount of dimensional shrinkage involved.
But since these were mostly used at that time only on small lesions on
front teeth, the potential damage was minimized. Composite was still a
big improvement in some ways over what was used before--acrylic resins
and silicate cements.
Amalgam does not adhere to the tooth, but it does expand on setting.
The dimensional change is much less than that of even the best composite
resins, but it cannot be bonded effectively (the Parkell company on Long
Island was claiming for a while that their product "amalgambond" could
bond amalgam, but I have my doubts about that--I can't even conceive of
how that would work.
Amalgam does leak--esp. initially, until it tarnishes. In the old days
we would line the cavity with copal varnish to seal the margins until
then, but in the 1970s some copper was included in the alloy mixes know
as "dispersed phase" alloys. These had improved marginal qualities,
esp. over time, and we stopped using varnishes.
All restoratives leak--those that set in the mouth (composites,
amalgams etc. may have setting expansion or contraction), and even those
that are formed outside of the mouth may leak as a result of differences
in coefficients of thermal expansion between the restorative and tooth
structure. Probably the best restorative in this regard is condensed
gold, but these are very labor intensive and time consuming to place,
and are seldom seen in the world outside of dental licensure exams.

Steve

--
Mark & Steven Bornfeld DDS
http :// www .dentaltwins,com
Brooklyn, NY
718-258-5001

Re: How do amalgam fillings work?

On Jun 5, 10:11 am, Mark & Steven Bornfeld
<bornfeldm...@dentaltwins,com >
>         Amalgam does leak--esp. initially, until it tarnishes.

Do any amalgams installed every increase Hg release rate, due to
factors such
as crevice corrosion, galvanism etc.

I would agree that a *typical* amalgam would initially have the
highest leakage, then it would decrease (as it expands) but, -this is
something I also thought about, but haven't really investigated in
detail-every surface on the amalgam "leaks". Therefore will a
protective oxidative layer form on the surfaces inside the tooth?

Re: How do amalgam fillings work?

Simplicio wrote:
> On Jun 5, 10:11 am, Mark & Steven Bornfeld
> <bornfeldm...@dentaltwins,com >
>> Amalgam does leak--esp. initially, until it tarnishes.
>
> Do any amalgams installed every increase Hg release rate, due to
> factors such
> as crevice corrosion, galvanism etc.
>
> I would agree that a *typical* amalgam would initially have the
> highest leakage, then it would decrease (as it expands) but, -this is
> something I also thought about, but haven't really investigated in
> detail-every surface on the amalgam "leaks". Therefore will a
> protective oxidative layer form on the surfaces inside the tooth?


I'm sure you realize that I'm using "leakage" in the sense that fluids
percolate through the margin between the filling and tooth structure,
not in the sense of mercury "leakage".
Empirically it's clear to me that oxidation does occur some distance
from the cavo-surface margin, but dye studies generally show less
leakage the further one gets from the surface of the restoration, so the
depth of any oxidized silver, mercury or other salts would be expected
to vary.

Steve

--
Mark & Steven Bornfeld DDS
http :// www .dentaltwins,com
Brooklyn, NY
718-258-5001

Re: How do amalgam fillings work?

"Mark & Steven Bornfeld" <bornfeldmung@dentaltwins,com > wrote in message
news:LuS1k.2532$Yw1.606@trndny02...
> Robert wrote:
>> Just out of curiousity, how do amalgam fillings work? Composite fillings
>> need some sort of adhesive. How do amalgams adhere to the teeth?
>>
> Amalgam does not adhere to the tooth, but it does expand on setting. The
> dimensional change is much less than that of even the best composite
> resins, but it cannot be bonded effectively (the Parkell company on Long
> Island was claiming for a while that their product "amalgambond" could
> bond amalgam, but I have my doubts about that--I can't even conceive of
> how that would work.

That is interesting. I once had an amalgam filling that was put into a
cracked tooth where half the tooth in the back was missing. I wonder what
held the amalgam in since there was little or no "other side" of the tooth.

Does that mean that amalgams eventually crack teeth? If so, do they do so
more or less than composites?

Re: How do amalgam fillings work?

Robert wrote:
> "Mark & Steven Bornfeld" <bornfeldmung@dentaltwins,com > wrote in message
> news:LuS1k.2532$Yw1.606@trndny02...
>> Robert wrote:
>>> Just out of curiousity, how do amalgam fillings work? Composite fillings
>>> need some sort of adhesive. How do amalgams adhere to the teeth?
>>>
>> Amalgam does not adhere to the tooth, but it does expand on setting. The
>> dimensional change is much less than that of even the best composite
>> resins, but it cannot be bonded effectively (the Parkell company on Long
>> Island was claiming for a while that their product "amalgambond" could
>> bond amalgam, but I have my doubts about that--I can't even conceive of
>> how that would work.
>
> That is interesting. I once had an amalgam filling that was put into a
> cracked tooth where half the tooth in the back was missing. I wonder what
> held the amalgam in since there was little or no "other side" of the tooth.


Sometimes it's magic. Seriously, I've seen restorations like this with
no visible means of support that have remained for many years. Clearly
there must be some retentive elements somewhere within the cavity
preparation. Dynamics of chewing must also play a role.
>
> Does that mean that amalgams eventually crack teeth? If so, do they do so
> more or less than composites?


This one has been batted around for years, and I haven't heard a
satisfactory answer. Undoubtedly this is because there are so many
factors involved in longevity of a filling, fracture of teeth, etc.
Generally speaking, the teeth that crack are the teeth where good
guidelines for restorations are ignored. Bill (dentaldoc) alluded to
cavity forms for amalgams, first codified by G.V. Black almost 150 years
ago (and modified by Bronner). Specifically, because of the prismatic
nature of amalgam, restorations should never be made that are more than
1/3 the distance between the cusp tips. Cavity preparations wider than
this should be extended over the side of the tooth.
These guidelines are routinely ignored, because people don't want
amalgam showing on the sides of the teeth. In these cases, it is
impossible to tell if the fracture has occurred as a consequence of
amalgam expansion, or of leaving what's called "unsupported" amalgam in
the prepared tooth. I suspect it's a combination of both, but for sure
narrower amalgams are much less likely to fracture the teeth.
I can't say overall that there is a greater or lesser chance of
fracture with composite. In my office, there is certainly a greater
incidence of recurrent decay in composites. This is doubtless mostly in
those cases in which the margin ends partially on enamel and partially
on dentin.

Steve
>
>
>
>
>


--
Mark & Steven Bornfeld DDS
http :// www .dentaltwins,com
Brooklyn, NY
718-258-5001

Re: How do amalgam fillings work?

On Jun 5, 11:37 am, Mark & Steven Bornfeld
<bornfeldm...@dentaltwins,com > wrote:
> Robert wrote:
> > "Mark & Steven Bornfeld" <bornfeldm...@dentaltwins,com > wrote in message
> >news:LuS1k.2532$Yw1.606@trndny02...
> >> Robert wrote:
> >>> Just out of curiousity, how do amalgam fillings work? Composite fillings
> >>> need some sort of adhesive. How do amalgams adhere to the teeth?
>
> >> Amalgam does not adhere to the tooth, but it does expand on setting. The
> >> dimensional change is much less than that of even the best composite
> >> resins, but it cannot be bonded effectively (the Parkell company on Long
> >> Island was claiming for a while that their product "amalgambond" could
> >> bond amalgam, but I have my doubts about that--I can't even conceive of
> >> how that would work.
>
> > That is interesting. I once had an amalgam filling that was put into a
> > cracked tooth where half the tooth in the back was missing. I wonder what
> > held the amalgam in since there was little or no "other side" of the tooth.
>
>         Sometimes it's magic.  Seriously, I've seen restorations like this with
> no visible means of support that have remained for many years.  Clearly
> there must be some retentive elements somewhere within the cavity
> preparation.  Dynamics of chewing must also play a role.
>
>
>
> > Does that mean that amalgams eventually crack teeth?  If so, do they do so
> > more or less than composites?
>
>         This one has been batted around for years, and I haven't heard a
> satisfactory answer.  Undoubtedly this is because there are so many
> factors involved in longevity of a filling, fracture of teeth, etc.
> Generally speaking, the teeth that crack are the teeth where good
> guidelines for restorations are ignored.  Bill (dentaldoc) alluded to
> cavity forms for amalgams, first codified by G.V. Black almost 150 years
> ago (and modified by Bronner).  Specifically, because of the prismatic
> nature of amalgam, restorations should never be made that are more than
> 1/3 the distance between the cusp tips.  Cavity preparations wider than
> this should be extended over the side of the tooth.
>         These guidelines are routinely ignored, because people don't want
> amalgam showing on the sides of the teeth.  In these cases, it is
> impossible to tell if the fracture has occurred as a consequence of
> amalgam expansion, or of leaving what's called "unsupported" amalgam in
> the prepared tooth.  I suspect it's a combination of both, but for sure
> narrower amalgams are much less likely to fracture the teeth.
>         I can't say overall that there is a greater or lesser chance of
> fracture with composite.  In my office, there is certainly a greater
> incidence of recurrent decay in composites.  This is doubtless mostly in
> those cases in which the margin ends partially on enamel and partially
> on dentin.
>
> Steve
>
>
>
> --
> Mark & Steven Bornfeld DDS http :// www .dentaltwins,com
> Brooklyn, NY
> 718-258-5001- Hide quoted text -
>
> - Show quoted text -

I've experienced the same in my office. Composite restorations
do have recurrent decay because they're so dependent upon
the bonding technique (and with dentists trying to get them
done faster... there will probably occur more often)

The amalgams do leak too but the corrosion does have something
to do with the recurrent decay.

You would expect the opposite (more decay without bonding as in
the amalgam). But the proof lies in the clinical world.

Dr. Marvin

http :// www .drmarvin,com

Re: How do amalgam fillings work?

Hey Marvin,,,,,,, have you checked out Dentaltown,com ??

--
/

Amatus

/
"DrMarvin/Natural Dentist" <powaydentist@gmail,com > wrote in message
news:a99dd52b-d527-4f3f-aa93-ef383eddfea8@z16g2000prn.googlegroups,com ...
On Jun 5, 11:37 am, Mark & Steven Bornfeld
<bornfeldm...@dentaltwins,com > wrote:
> Robert wrote:
> > "Mark & Steven Bornfeld" <bornfeldm...@dentaltwins,com > wrote in message
> >news:LuS1k.2532$Yw1.606@trndny02...
> >> Robert wrote:
> >>> Just out of curiousity, how do amalgam fillings work? Composite
> >>> fillings
> >>> need some sort of adhesive. How do amalgams adhere to the teeth?
>
> >> Amalgam does not adhere to the tooth, but it does expand on setting.
> >> The
> >> dimensional change is much less than that of even the best composite
> >> resins, but it cannot be bonded effectively (the Parkell company on
> >> Long
> >> Island was claiming for a while that their product "amalgambond" could
> >> bond amalgam, but I have my doubts about that--I can't even conceive of
> >> how that would work.
>
> > That is interesting. I once had an amalgam filling that was put into a
> > cracked tooth where half the tooth in the back was missing. I wonder
> > what
> > held the amalgam in since there was little or no "other side" of the
> > tooth.
>
> Sometimes it's magic. Seriously, I've seen restorations like this with
> no visible means of support that have remained for many years. Clearly
> there must be some retentive elements somewhere within the cavity
> preparation. Dynamics of chewing must also play a role.
>
>
>
> > Does that mean that amalgams eventually crack teeth? If so, do they do
> > so
> > more or less than composites?
>
> This one has been batted around for years, and I haven't heard a
> satisfactory answer. Undoubtedly this is because there are so many
> factors involved in longevity of a filling, fracture of teeth, etc.
> Generally speaking, the teeth that crack are the teeth where good
> guidelines for restorations are ignored. Bill (dentaldoc) alluded to
> cavity forms for amalgams, first codified by G.V. Black almost 150 years
> ago (and modified by Bronner). Specifically, because of the prismatic
> nature of amalgam, restorations should never be made that are more than
> 1/3 the distance between the cusp tips. Cavity preparations wider than
> this should be extended over the side of the tooth.
> These guidelines are routinely ignored, because people don't want
> amalgam showing on the sides of the teeth. In these cases, it is
> impossible to tell if the fracture has occurred as a consequence of
> amalgam expansion, or of leaving what's called "unsupported" amalgam in
> the prepared tooth. I suspect it's a combination of both, but for sure
> narrower amalgams are much less likely to fracture the teeth.
> I can't say overall that there is a greater or lesser chance of
> fracture with composite. In my office, there is certainly a greater
> incidence of recurrent decay in composites. This is doubtless mostly in
> those cases in which the margin ends partially on enamel and partially
> on dentin.
>
> Steve
>
>
>
> --
> Mark & Steven Bornfeld DDS http :// www .dentaltwins,com
> Brooklyn, NY
> 718-258-5001- Hide quoted text -
>
> - Show quoted text -

I've experienced the same in my office. Composite restorations
do have recurrent decay because they're so dependent upon
the bonding technique (and with dentists trying to get them
done faster... there will probably occur more often)

The amalgams do leak too but the corrosion does have something
to do with the recurrent decay.

You would expect the opposite (more decay without bonding as in
the amalgam). But the proof lies in the clinical world.

Dr. Marvin

http :// www .drmarvin,com

Re: How do amalgam fillings work?

On Tue, 10 Jun 2008 16:42:48 -0400, "Amatus Cremona"
<Nicola@sottovocce,com > wrote:

>Hey Marvin,,,,,,, have you checked out Dentaltown,com ??
>
>--
>/
>
>Amatus


He prolly got kicked from there.

Re: How do amalgam fillings work?



What you are seeing is probably more telling to the work
done in many dental offices instead of the materials
themselves.

My son's girl friend is starting dental hygiene school in
August, and currently works in a suburban dental office
as a hygiene assistant.

She was telling me last night how the office diagnoses
sealants for a lot of teeth (which may be OK), but has
the assistants (few of which have any formal training)
place them. They had her place 4 sealants on a patient
yesterday and she has only worked in the office for a month
with no previous experience.

They are bonding over crud in the grooves without using
air abrasion or a laser to properly clean them. She also
mentioned that there seems to be a lot of sealants coming
off from previous visits (big surprise...not).

She isn't on the operative side of the office, but one
would suspect if they are sloppy on sealants, they may well
be sloppy in other aspects of care.

D




> I've experienced the same in my office. Composite restorations
> do have recurrent decay because they're so dependent upon
> the bonding technique (and with dentists trying to get them
> done faster... there will probably occur more often)
>
> The amalgams do leak too but the corrosion does have something
> to do with the recurrent decay.
>
> You would expect the opposite (more decay without bonding as in
> the amalgam). But the proof lies in the clinical world.
>
> Dr. Marvin

Re: How do amalgam fillings work?

Looks like your son will have to continue having his dental work done by his
father, rather then let love take over and assure his girlfriend she is the
best.
Gail

Re: How do amalgam fillings work?


She's aware of the type of office she is in, and my son is applying to
dental school this summer, so I won't remain so important forever.

;-)
D

news.chi.sbcglobal,net wrote:

> Looks like your son will have to continue having his dental work done by his
> father, rather then let love take over and assure his girlfriend she is the
> best.
> Gail
>
>

Re: How do amalgam fillings work?

You are such a sweet guy. you will remain forever important.
Gail

"Dartos" <tuthjockey@myturbonet,com > wrote in message
news:1213208762_209009@news.newsville,com ...
>
> She's aware of the type of office she is in, and my son is applying to
> dental school this summer, so I won't remain so important forever.
>
> ;-)
> D
>
> news.chi.sbcglobal,net wrote:
>
>> Looks like your son will have to continue having his dental work done by
>> his father, rather then let love take over and assure his girlfriend she
>> is the best.
>> Gail
>>
>>
>

Re: How do amalgam fillings work?



news.chi.sbcglobal,net wrote:
> You are such a sweet guy. you will remain forever important.
> Gail

Thanks, but Bornfeld is the gentleman in this group.

:-)
D

Re: How do amalgam fillings work?

Dartos wrote:
>
>
> news.chi.sbcglobal,net wrote:
>> You are such a sweet guy. you will remain forever important.
>> Gail
>
> Thanks, but Bornfeld is the gentleman in this group.
>
> :-)
> D
>
STFU! ;-)

--
Mark & Steven Bornfeld DDS
http :// www .dentaltwins,com
Brooklyn, NY
718-258-5001