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BPA and Dental Composites - Are They SAFE ?
and Other Estrogenic chemicals found
in Dental Composite Fillings
no dental material known that has no known or suspected toxic potential!
They are ALL potentially toxic to some degree! But some are much
worse than others!!!!
Recently, many patients have become
concerned and emailed me asking about the possible toxicity of dental
composite filling / bonding materials. There has been concern
that they may have hormone-like behavior. It has been reported that they
contain "BPA" - bisphenol-A - which is thought to act as an
estrogenic substance and is said to have endocrine-disrupting
There are many questions to be
concerned about this. First, if used in the teeth of very young
children, could it have a hormonal effect on their development? If
used in women's teeth, could it promote hormonal changes
or even stimulate estrogen-sensitive cancers, like some types of breast
cancers? Could it have a feminizing [estrogenic] effect on men?
These are all fair and reasonable and scary questions!
Why is it important
In my practice, I see many patients
that want to get rid of their silver-mercury [amalgam]
fillings because they are concerned about the potential toxicity of
mercury. [ All amalgam fillings are one-half made up of mercury!
] There are other articles on this site more about amalgams and
mercury. When amalgams are removed the most common material used to
replace them is "composite", which is basically a hard plastic material
filled with tiny, powdered, tightly packed, granules of ground up
glass, porcelain, quartz, silica and other materials to give it the
color, hardness, and toughness it needs for a particular type of filling
People that are concerned enough
about the toxicity of mercury to have their fillings removed and
replaced, certainly don't want to get rid of one toxic material, just to
have another different one put in, right? Right!
I have been looking at the research
literature to try to get a handle on this difficult question. The
ADA and other organizations tend to say "don't worry, it's fine"....
but they have also been saying that about the mercury in amalgam for a
hundred and fifty years, so who do we believe? In
looking at the literature and hearing information at continuing
education courses, I have begun to feel more comfortable with some
general conclusions, which I will try to share here.
The present situation as I see it is
this. With possibly one exception that I know of, all composite
filling / bonding materials are just about the same chemically. They
may differ a little here and there for several reasons but their basic
chemistry is very closely related to each other.
Now, having said that, I have to add
this. Composites are basically "plastics" as far as their
chemistry goes, and "plastics" are very complicated. They are also
all around us, used in almost everything we see, touch, and use every day
in one form or another. The cars we drive - that used to be
made of steel - are almost half made of plastics now! and so it
is from our expensive filtered water bottles, to our iPhones and
computers, from our baby bottles and toys to the lining inside the
cans of food we buy at the market. To AVOID plastics in this day and
age, is almost impossible ....you'd have to work very hard at it,
The problem with plastics
being "complicated" is that the industrial processes that are involved in
making them are also very complicated and complex. Many steps are involved
and depending on the degree of "quality control" used in the manufacture
of them, there may be more or less "impurities" produced and left in them.
Impurities are undesirable chemicals that were never meant to be in there
but are accidental by-products of complicated chemical reactions used to
make the plastics. Or they can be undesirable by-products that
are expected and known about, but not adequately and
completely enough removed. You could almost think of it
as the process of planting a lawn. If you do it carefully,
using good seed and dirt and fertilizers and good technique,
you get a good thick lush lawn with no weeds. Do
it less carefully and you get weeds, brown, bare spots and so on. Still a
lawn, but not nearly as good.
The other problem with it being
complicated that I think of is that there are many complicated chemicals
produced by the reactions so that the chemistry is much more than
just what is mixed together in the beginning, because those things react
with each other and produce a whole bunch of other things, sometimes
only temporarily and sometimes they stay in there. So
when we talk about "BPA" we are really talking about a long list of
somewhat related but still different chemicals that differ slightly by
brand and by quality control.....I hope I haven't just made it more
confusing than ever for you!
How to make Sense out of it All
I came across what I thought was
an interesting and informative research article
http://jdr.iadrjournals.org/cgi/reprint/83/3/222.pdf that I will
try to highlight what I think are the important points.
The authors of the paper state
clearly that certainly "the release of estrogenic compounds from
composite is ...undesirable" . But they researched 24 popular
composite materials to determine the level of BPA's in them and the makeup
of that BPA and the estrogenicity of each brand of composite tested.
Compared to a "control" sample which
was not estrogenic and just used for comparison, they found a
significant range among the 24 composites. Six of them were much more
estrogenic than the control and the others were very close to or
even less than the control. Since the control was realistically
"zero" the slight variations must be, I concluded, due to slight
inaccuracies in the technique or the instrumentation used to get the
measurements. Keep in mind that we are dealing here with EXTREMELY
SMALL AMOUNTS of chemicals being measured. Like trying to measure
the length of a flea with a ruler!
seemed to conclude that while more research should be done, the
results they got, strongly suggest that the amount of estrogenic
effect is VERY SLIGHT and probably negligible for humans.
studies had also shown that the levels of BPA in composite were in
the range of a hundred times LOWER than what was thought to be
acceptable exposure [by the Canadian government which tends to be
more strict on such issues than in the USA].
highly recommend looking at an article written for IAOMT -International
Organization of Medical Toxicology - an excellent organization
for dentists and physicians and researchers dedicated to non-toxic
treatment. They are into scientifically verified procedures
rather than "trendy, holistic-sounding but unproveable ideas.
What Do I do?
First, studies like this one help
guide me in the choices of which products I chose to buy and use. It
helps to verify what I have long thought that good name brand
manufacturers tend to have better quality control.
Usually, but not always, they charge more for their products and it's
worth it. 3M is one, but not the only, such good company in my
view. Off-brand, generic, products, may be just as good in
some cases but there's a level of trust missing with them. You never
know who's actually making the stuff and it could change from month to
month and still end up with the same label on it at the end! We all
remember the toys from China with the lead-paint !
Another idea that seems to make
sense recently to me is that rinsing well after getting a composite
filling is a good idea because much of the various BPA chemicals end
up in your saliva and can be washed out. And while spitting them
down the sink is not the greatest thing, it's better than keeping it
in your mouth to be swallowed.
Luckily, research shows that
unlike the mercury in amalgam fillings, which is released constantly over
years and years for as long as the amalgam is there, the BPA's and related
compounds are released mostly when the composite filling is
first done and chemically or light cured [hardened] , and then drops off
rapidly after that to almost nothing for the duration of the life of the
The Near Future
There is a lot of concern about
composites and a lot of money to be made in the making and selling
of them by dental materials manufacturers. Manufacturers are
concerned about the public's anxiety about BPA and other possibly toxic
ingredients and they are aware of regulations limiting or banning it
in this country and in other countries. So I can't imagine it will
be long before they find a way to make composites without
these undesirable compounds or with levels so low that they will be
There is one composite, as I
mentioned in the beginning, that is claimed by many holistic
dentists to have no BPA's. It's
chemistry is a bit different than all the others as far as I can tell, so
perhaps it's true. It is called Diamond Crown, Diamond Flow,
Diamond Lite etc. I have recently gotten some
literature from the manufacturer [or perhaps it's just the distributor],
and it looks very interesting. I asked for research articles
and what I got was pretty old and not really dealing with the questions
discussed here. I have not, unfortunately, been able to find
reliable scientific research to back up the claim of no BPA made
by many of its supporters. While they claim to be "non-toxic"
they don't specifically mention BPA or the sub-chemicals resulting from
dentists claim it to be a fact that the "Diamond" products are free
of BPA and other undesirable compounds; however, I have found
nothing in the literature to back up that claim. That bothers me!
There is a fairly
new Composite material from a German manufacturer Heraeus-Kulzer,
called Venus Diamond. It claims to be totally BPA-free.
I wonder if they didn't buy the "Diamond..." line of products
mentioned above and put a new name on them, but I'm not sure.
I have not used the Venus Diamond composite. I imagine it's
pretty good but I had a bad experience with Kulzer several years ago when
I used another composite product they promoted heavily and it seemed
to be great, but it turned out to be pretty bad! Nothing to do
with any toxic ingredients, but still it did not begin to live up to the
advertizing hype they put out. So I have
very limited confidence in Kulzer even though they are a large major
manufacturer of dental materials. My experience probably is the
exception to the rule and most of their products are probably very good -
still it made me skeptical of what [any] manufacturers say about their
newest and greatest pruducts.
As far as I can tell now, the
Kulzer Venus Diamond is not at all related to the Diamond Crown, Diamond Flow,
Diamond Lite [mentioned above] materials made by a Canadian
manufacturer, I believe. I'm not sure if the Kulzer products are bpa
free but searching the MSDS sheets does not indicate any bpa
that I could see. The Canadian Diamond Crown, Diamond Flow,
Diamond Lite composites are, I believe totally free of bpa because
they are based on a very different chemistry. They are phenolic
plastics, whereas the American and European composites seem to be
methacrylate plastics. I hope that's helpful and not more confusing!
Then there's the question of whether phenolic plastics pose a different
kind of possible toxicity? Generally speaking phenolics are not good
things but perhaps it it's ok in this form.
know of what looks like a reliable research article that shows the
Diamond line of composite materials - or any other composite
product for that matter - to be free of potentially toxic
compounds, please email that info to me so I can share it with
With considerable interest from
you, the readers and followers of my website, I have tried to keep
up with changes in the dental composite technology. I recently
came across ESSTECH, a company that manufactures chemicals used in the
manufacture of dental composite. They have a patented BisGMA that,
apparently is sold to dental manufacturers. They claim that their
BisGMA is different from others in that it releases so much
less bpa than other BisGMA's that composites using their BisGMA is
"considered to be essentially bpa-free".
I asked them which composites
use their BisGMA, and they told me the line of ULTRADENT Composites use
it and therefore are considered bpa-free. ULTRADENT makes several
composite materials which you can look up since each has a
different name and a slightly different suggested use.
This makes it confusing because
when I look up the ingredients for a composite material, if I see
it contains BisGMA or similar chemistry, I have always assumed it has
bpa. So, maybe this changes things. I'm not absolutely sure
at this point but it seems interesting and worth keeping an eye
It seems to me, as I have stated
many times in other articles on this website [which I strongly
encourage you to read], that there is no dental material known
that has no known or suspected toxic potential! They are
ALL potentially toxic to some degree! But some are much more so
than others!!!! So while there are some legitimate
concerns about specific ingredients in composite filling materials, it
does seem to me that while there is some risk, that risk appears to
be VERY SMALL when viewed in its proper context and when compared to
other materials available to use.
An exception to this statement might
be that there may be some people that could have specific - and unusual -
allergies to, or hypersensitivity to the specific chemical compounds found
in dental composites. That would not apply to most of us.
March 2013 update
As I have
expressed above, quality control in the manufacture of composite
material seems to me to be crucial in limiting the undesirable by-products
and contaminants in the end process of what is a very complex set of
chemical reactions and processes. That is why I believe it is
so important to stick to reliable solid manufacturers that have a good
track record of quality control. There are many "generics" out there
sold by dental suppliers that could be made one month by a factory
in the USA and the next month in a factory in China or Mexico where the
quality control might be better or worse. All of them would likely
have the same labels and MSDS sheets. A recent lengthy article seems
to me to support the idea that quality control is perhaps the
key factor in keeping the BPA to a minimum or even absent in the final
product. It's a bit much to read but I know some of you want as much
information as possible.
July 2013 update
composites Venus Diamond, Venus Pearl and, I believe, Venus Diamond Flow
are all supposedly based on a different chemistry using Urethane instead
of the common methyl methacrylate used in just about all other composites
as far as I can tell. As a result of this, Kulzer claims these
composites are completely bpa-free.
Bisphenol A in Dental Materials
The issue. The controversy about Bisphenol A (BPA) and its potential
impact on health and human development received increased media
attention in the past year. Headlines have linked BPA to heart
disease, coronary artery disease, obesity, diabetes, and immune system
and reproductive disorders.
BPA is a common component used to make polycarbonate plastic and epoxy
resins. Polycarbonate plastics are found in countless everyday items
such as food and beverage containers, eye glasses, cell phones, bike
helmets, children’s toys, plastic tableware, some types of receipts,
self-adhesive labels and a host of other consumer products. Epoxy
resins are often used as protective coatings inside metal food cans.
The primary source of exposure to BPA for most people is assumed to
occur through the diet1 although industrial and household wastes
released into the environment are other sources.
BPA, which has been used in consumer products since the 1960s, was
used in the manufacture of some dental materials.2-4 Dental sealants
were identified in 1996 as a source of very low-level BPA exposure5
and a recent study published in the Journal of the American Dental
Association reports that “placement of resin-based composite
restorations was associated with detectable increases in saliva of BPA
and other study compounds within one hour after restoration placement
and increased concentration of BPA in urine nine to 30 hours after
Some manufacturers of dental composites and sealants market their
products as “BPA-free,” yet some studies have detected BPA in the
saliva of patients within minutes following placement. BPA-free
usually means that no BPA is added to the product, or that residual
BPA is below the detection limit of the analytical method used to make
So, why would BPA appear in “BPA-free” dental materils?
Composite restorative materials are made from a mixture of ingredients
where bisphenol A glycidyl methacrylate (bis-GMA) is the major
component. BPA is a critical starting material used to manufacture
bis-GMA and many other methacrylates used in sealants and bonding
Looking at the structures of BPA and estradiol (Fig.1) you will find
similar features between the two compounds that impart at least some
ability for BPA to bind to mammalian estrogen receptors.5
Bis-GMA is an extremely viscous material making inclusion of
polymerization initiators very difficult without adding modifiers to
change its handling properties. An example of one of these modifiers
is bisphenol A dimethacrylate (bis-DMA), which, when mixed with
bis-GMA, reduces viscosity sufficiently to allow the addition of
stabilizers and polymerization initiators resulting in a homogeneous
mixture that is easily handled. BPA also is used to synthesize bis-DMA.
Materials containing bis-DMA can release very small quantities of BPA
after coming in contact with salivary enzymes (esterases) (Fig.2).7
Several alternative aliphatic viscosity modifiers often are used
instead of bis-DMA. One of these alternatives is TEGDMA, which is not
synthesized from BPA, nor does it decompose to BPA (Fig 3).
Materials made with bis-GMA do not undergo esterase hydrolysis.7
Sealants, bonding agents and composite resins developed with bis-DMA
and/or bis-GMA may contain trace amounts of BPA as a byproduct of the
manufacturing process. Careful formulation during the manufacturing
process for bis-GMA keeps the unreacted levels of BPA to a minimum,
but some residual trace levels of BPA can remain. Manufacturers of
materials containing dental resins do not manufacture bis-GMA
themselves. Bulk bis-GMA is purchased from at least 22 worldwide
suppliers of bis-GMA.8 Four suppliers are based in the United States,
11 in mainland China, three in Hong Kong, three in Germany and one in
the United Kingdom. It is unknown how well residual levels of BPA are
controlled among these manufacturers.
Polymerization of bis-GMA containing materials involves free-radical
chemical reactions. Oxygen in the air interferes with this process
causing incomplete polymerization at the bis-GMA/air interface. Thus,
any newly placed restoration or sealant will have a thin surface layer
of incompletely polymerized material, which is rapidly lost within
hours post-placement. This could be the reason that the Kingman study6
detected higher levels of composite components (including BPA as well
as bis-GMA) in saliva and urine after placement than before placement.
However, as in other studies, component release became significantly
reduced or undetectable within hours,6 and exposure to these
substances seems to be acute, not chronic.
What level of BPA exposure produces harmful effects in humans?
This is a key question and the subject of active research today. A
decade or more ago, several studies showed that clinical levels of BPA
in various body fluids were transient and rapidly fell below the
detection limit of 1.0 to 5.0 ng/mL (1.0 - 5.0 ppb) by the high
pressure liquid chromatography (HPLC) methods used at that time.
However, a proliferation of subsequent studies using more sensitive
liquid chromatography/mass spectrometry (LCMS) analytical methods
reduced BPA detection limits to 0.02 ng/mL (50 times lower). The more
sensitive methods appeared capable of detecting BPA at significantly
lower levels than the earlier methods. Furthermore, other studies
implicated dental resins as a potential cause of harmful effects such
as neurobehavioral disorders9 or obesity in children.10 In an apparent
response to concerns surrounding potential harmful effects of dental
resins, many dental resin manufacturers have stated that their product
contains no detectable level of BPA. However, manufacturers often do
not state the detection limit or the analytical method employed. Any
dental material made with bis-GMA potentially can contain trace levels
The fact that the presence of a perceived harmful material can be
detected does not mean the material is harmful at that detection
limit. More than 500 years ago, a German physician, Philippus von
Hohenheim, better known as Peracelsus, stated:
“All substances are poisons; there is none which is not poison. The
right dose differentiates a poison from a remedy.”11
In other words, the dose makes the poison. This is an extremely
important concept that the dental professional always must be mindful
of when evaluating studies or reports claiming that a toxic substance
was found in a dental material.
Patients may be alarmed by media reports of environmental exposure to
BPA from a multitude of common items, and the media reports usually
mention dental materials in the same breath.
Acceptable BPA exposure limits are:
EPA:12 <0.05 mg/kg body weight/24 hours, which is the same as <50,000
Thus for a 70 kg man = 3.5 x 106 ng/day, and for a 10 kg child = 0.5 x
The National Toxicology Program (NTP)17
suggested: 10,000 ng/kg/day
The recent Kingman study6 measured BPA concentrations in the saliva of
study subjects before and after placement of a composite resin
restoration. Salivary concentrations of BPA should represent the
highest measurable indicator of BPA exposure from composite resin,
since saliva is in direct contact with the resin. Salivary
concentration should thus be a good indicator of exposure. Salivary
BPA measured before placement accounts for any BPA exposure from
pre-existing sources and serves as a baseline level. Subtracting the
BPA concentrations following placement is an indicator of the amount
of BPA originating directly from the composite.
Geometric means were calculated for three sampling periods
post-placement: 0-1; 1-8; and 9-30 hours. The geometric mean average
of BPA in saliva within the first hour of placement was 0.21 ng/mL.
Following composite placement from one to 30 hours, BPA was not
detected in saliva at levels above baseline.6 This indicates that BPA
exposure from composite placement is very short and does not persist
in saliva in detectable amounts after 60 minutes.
Therefore, these data suggest that the estimated oral BPA exposure
from one composite resin restoration over 24 hours is 0.00875 ng/mL
saliva/hour. A nanogram is one-millionth of a mg. If we assume average
saliva production of 0.5 mL/minute or 30 mL/hour, and an average body
weight of 70 kg for each study participant, then the BPA exposure
following composite placement is about 6.3 ng/70 kg within the first
hour. Since salivary BPA levels were not significantly different from
pretreatment baseline levels after one hour and up to 30 hours
post-treatment, the average adult daily dose of BPA from one composite
resin restoration was 6.3 ng. Another study looked at BPA in saliva
following sealant (no bis-DMA) placement in adults. Analysis found an
average of 0.32 ng/mL of BPA in saliva immediately following
treatment, and essentially no BPA was detected in saliva in excess of
pretreatment levels one hour after placement of sealant on an average
of six teeth.13
The above two clinical studies show that BPA exposure from current
bis-GMA based composites and sealants is more than 500,000 times lower
than the EPA acceptable daily exposure limit for adult humans. If the
more conservative NTP exposure limit is used, then BPA exposure from
one composite is more than 100,000 times lower. The margin of safety
is several orders of magnitude lower than either exposure limit. Trace
levels of BPA from dental resins do not appear to present a health
hazard based on current exposure limits, especially when one considers
that the exposure predominantly is acute only during the first hour
Urethane modified methacrylate restorative resins (UDMA) are available
and are not manufactured from BPA (Fig. 4). However, their use as a
bis-GMA resin alternative is limited because they do not develop
equivalent stiffness and hardness characteristics as bis-GMA based
restoratives.14 Consequently, use is restricted primarily to
Some earlier studies in rodents suggested significant harmful
reproductive effects from very low levels of BPA exposure, much lower
than the EPA acceptable level, and may have raised concerns that
similar exposure levels could have the same effect in humans. However,
recent studies have challenged that notion by showing that primates
metabolize ingested BPA differently from rodents. Newborn monkeys were
found to have a high capacity for inactivating BPA in contrast to
newborn rodents. Blood levels of equivalent BPA exposures were found
to be 10-fold lower in rhesus monkeys than in rats and mice.15 Another
study showed that people who ingested high levels of BPA in their diet
did not show high levels of BPA in their blood, which supported
findings in the primate studies.16
Despite an absence of documented adverse health risks related to these
dental materials, some patients may be concerned. Nevertheless, the
benefits of composite resin materials for restoring oral health and
preventing caries is well established, while any health risks from
their use is not. In 2007, the U.S. Department of Health and Human
Services stated that, “Dental sealant exposure to bisphenol A occurs
primarily with the use of dental sealants [containing] bisphenol A
dimethacrylate. This exposure is considered an acute and infrequent
event with little relevance to estimating general population
exposures.”17 Furthermore, the medical community continues to support
the use of resin-based dental materials based on their proven benefits
and brevity of BPA exposure.18
(Editor’s note: A future issue of the ADA Professional Product Review
will feature “An Evaluation of Bisphenol A found in Dental Materials,”
in which we will report ADA Laboratory test results of BPA and bis-DMA
levels from a variety of dental composites, sealants and bonding
materials. Although these data will not use human subjects, they will
give insight to the potential patient exposure levels of BPA from
known amounts of product resin.)
ABBREVIATION KEY Bisphenol A (BPA): A chemical produced in large
quantities for use primarily in the production of polycarbonate
plastics and epoxy resins. Bis-GMA: Bisphenol A-glycidyl methacrylate.
Bis-DMA: Bisphenol A-dimethacrylate. TEGDMA: Triethylene glycol
dimethacrylate. UDMA: Urethane dimethacrylate.
This article was written in
the hope that it will increase understanding about a topic that seems
important from time to time. Obviously it is only a part of the whole
story, so if you have questions after reading this please do not hesitate
to ask or email. Also, if there is a topic that
you think would be helpful, please suggest it. Does this help you? Let me
TOPICS / INFO
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Michael C. Goldman DDS
General and Cosmetic Dentistry
3815 East-West Highway
Chevy Chase, Maryland 20815
Phone (301) 656-617
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in dentistry is an approach
to dental treatment, primarily caring for patients' health and safety from
both a conventional as well as "alternative healthcare" point of view.
It is sometimes called "biological" dentistry or
"biocompatible" dentistry. In it's fullest sense, I believe it
acknowledges and deals with the mind, body and spirit of the patient, not just his
or her "teeth". See Topics / Info.....
Cosmetic dentistry is about doing
quality , esthetic dentistry in a way that looks natural to begin with, and
furthermore, can even improve one's attractiveness through
techniques such as bonding, bleaching, veneers, caps, implants and more. It can
be like "instant orthodontics" in correcting crooked, twisted or
misplaced teeth in many instances. Dark or misshapen teeth can be restored.
Smiles that lack youthful vigor or beauty can be revitalized! See Topics / Info..
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